N-CSR

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-CSR

CERTIFIED SHAREHOLDER REPORT OF REGISTERED
MANAGEMENT INVESTMENT COMPANIES

Investment Company Act file number			811-10597
Tax-Managed Mid-Cap Core Portfolio
(Exact name of registrant as specified in charter)
The Eaton Vance Building, 255 State Street, Boston, Massachusetts					02109
(Address of principal executive offices)					(Zip code)
Maureen A. Gemma The Eaton Vance Building, 255 State Street, Boston, Massachusetts 02109
(Name and address of agent for service)
Registrant’s telephone number, including area code:				(617) 482-8260
Date of fiscal year end:	October 31
Date of reporting period:		October 31, 2008

Item 1. Reports to Stockholders

Tax-Managed Mid-Cap Core Portfolio as of October 31, 2008

PORTFOLIO OF INVESTMENTS

Common Stocks — 98.6%
Security	Shares		Value
Air Freight & Logistics — 2.0%
CH Robinson Worldwide, Inc.		27,200	$	1,408,416
			$	1,408,416
Auto Components — 0.8%
BorgWarner, Inc.		26,000	$	584,220
			$	584,220
Capital Markets — 4.7%
Affiliated Managers Group, Inc.(1)		21,000	$	973,980
Raymond James Financial, Inc.		57,000		1,327,530
SEI Investments Co.		53,000		937,040
			$	3,238,550
Chemicals — 2.4%
Albemarle Corp.		35,200	$	857,120
RPM International, Inc.		56,000		795,200
			$	1,652,320
Commercial Banks — 5.5%
City National Corp.		19,500	$	1,043,835
Cullen/Frost Bankers, Inc.		30,700		1,718,279
Westamerica Bancorporation		18,000		1,030,500
			$	3,792,614
Commercial Services & Supplies — 1.7%
Mine Safety Appliances Co.		43,000	$	1,161,000
			$	1,161,000
Construction & Engineering — 1.0%
Jacobs Engineering Group, Inc.(1)		20,000	$	728,600
			$	728,600
Construction Materials — 0.8%
Vulcan Materials Co.		10,000	$	542,800
			$	542,800
Containers & Packaging — 2.0%
Sonoco Products Co.		54,000	$	1,359,720
			$	1,359,720

Security	Shares		Value
Diversified Consumer Services — 2.8%
H&R Block, Inc.		40,000	$	788,800
Matthews International Corp., Class A		26,500		1,182,695
			$	1,971,495
Electric Utilities — 1.8%
DPL, Inc.		53,600	$	1,222,616
			$	1,222,616
Electrical Equipment — 2.0%
AMETEK, Inc.		42,000	$	1,396,500
			$	1,396,500
Electronic Equipment, Instruments & Components — 5.6%
Amphenol Corp., Class A		40,500	$	1,160,325
Mettler Toledo International, Inc.(1)		17,000		1,301,180
National Instruments Corp.		55,000		1,397,000
			$	3,858,505
Energy Equipment & Services — 4.3%
FMC Technologies, Inc.(1)		30,000	$	1,049,700
Helmerich & Payne, Inc.		28,000		960,680
Oceaneering International, Inc.(1)		35,000		985,950
			$	2,996,330
Food & Staples Retailing — 1.3%
Ruddick Corp.		32,000	$	916,480
			$	916,480
Food Products — 2.3%
Hormel Foods Corp.		26,000	$	734,760
McCormick & Co., Inc.		26,500		891,990
			$	1,626,750
Gas Utilities — 3.9%
AGL Resources, Inc.		36,100	$	1,097,440
National Fuel Gas Co.		22,000		796,180
Questar Corp.		23,400		806,364
			$	2,699,984

See notes to financial statements
17

Tax-Managed Mid-Cap Core Portfolio as of October 31, 2008

PORTFOLIO OF INVESTMENTS CONT'D

Security	Shares		Value
Health Care Equipment & Supplies — 7.0%
Bard (C.R.), Inc.		15,800	$	1,394,350
Beckman Coulter, Inc.		18,400		918,528
DENTSPLY International, Inc.		44,800		1,361,024
Mentor Corp.		31,000		523,900
Varian Medical Systems, Inc.(1)		14,000		637,140
			$	4,834,942
Health Care Providers & Services — 3.0%
Henry Schein, Inc.(1)		25,000	$	1,170,250
Patterson Cos., Inc.(1)		35,000		886,550
			$	2,056,800
Hotels, Restaurants & Leisure — 1.2%
Sonic Corp.(1)		79,850	$	854,395
			$	854,395
Household Durables — 1.6%
Mohawk Industries, Inc.(1)		12,800	$	619,264
Snap-On, Inc.		13,500		498,825
			$	1,118,089
Insurance — 3.9%
Brown and Brown, Inc.		55,000	$	1,128,600
HCC Insurance Holdings, Inc.		34,000		750,040
Markel Corp.(1)		2,300		806,932
			$	2,685,572
IT Services — 1.0%
Fiserv, Inc.(1)		20,200	$	673,872
			$	673,872
Life Sciences Tools & Services — 1.3%
Pharmaceutical Product Development, Inc.		30,000	$	929,400
			$	929,400
Machinery — 4.8%
Donaldson Co., Inc.		40,000	$	1,406,000
Graco, Inc.		29,200		722,116
IDEX Corp.		50,000		1,159,000
John Bean Technologies Corp.		6,480		54,302
			$	3,341,418

Security	Shares		Value
Media — 1.0%
John Wiley & Sons, Inc., Class A		21,000	$	730,380
			$	730,380
Metals & Mining — 1.0%
Commercial Metals Co.		66,000	$	732,600
			$	732,600
Multiline Retail — 2.7%
Dollar Tree, Inc.(1)		50,000	$	1,901,000
			$	1,901,000
Multi-Utilities — 3.6%
NSTAR		40,000	$	1,322,000
OGE Energy Corp.		42,300		1,154,790
			$	2,476,790
Oil, Gas & Consumable Fuels — 0.9%
Holly Corp.		32,000	$	628,160
			$	628,160
Personal Products — 2.7%
Alberto-Culver Co.		72,000	$	1,852,560
			$	1,852,560
Professional Services — 1.3%
FTI Consulting, Inc.(1)		15,000	$	873,750
			$	873,750
Real Estate Investment Trusts (REITs) — 3.3%
Health Care REIT, Inc.		30,000	$	1,335,300
Rayonier, Inc.		30,000		992,400
			$	2,327,700
Semiconductors & Semiconductor Equipment — 2.0%
Microchip Technology, Inc.		57,050	$	1,405,142
			$	1,405,142
Software — 5.5%
ANSYS, Inc.(1)		41,200	$	1,179,556
Citrix Systems, Inc.(1)		27,500		708,675

See notes to financial statements
18

Tax-Managed Mid-Cap Core Portfolio as of October 31, 2008

PORTFOLIO OF INVESTMENTS CONT'D

Security	Shares		Value
Software (continued)
Fair Isaac Corp.		30,000	$	467,700
Jack Henry & Associates, Inc.		78,500		1,492,285
			$	3,848,216
Specialty Retail — 3.7%
O'Reilly Automotive, Inc.(1)		48,000	$	1,301,280
Ross Stores, Inc.		38,500		1,258,565
			$	2,559,845
Tobacco — 1.0%
Universal Corp., VA		17,000	$	673,030
			$	673,030
Trading Companies & Distributors — 1.2%
Fastenal Co.		20,000	$	805,200
			$	805,200
Total Common Stocks (identified cost $69,160,617)			$	68,465,761
Total Investments — 98.6% (identified cost $69,160,617)			$	68,465,761
Other Assets, Less Liabilities — 1.4%			$	949,175
Net Assets — 100.0%			$	69,414,936

⁽¹⁾  Non-income producing security.

See notes to financial statements
19

Tax-Managed Mid-Cap Core Portfolio as of October 31, 2008

FINANCIAL STATEMENTS

Statement of Assets and Liabilities

As of October 31, 2008

Assets
Investments, at value (identified cost, $69,160,617)	$	68,465,761
Cash		976,153
Dividends and interest receivable		68,063
Total assets	$	69,509,977
Liabilities
Payable to affiliate for investment adviser fee	$	44,109
Payable to affiliate for Trustees' fees		264
Accrued expenses		50,668
Total liabilities	$	95,041
Net Assets applicable to investors' interest in Portfolio	$	69,414,936
Sources of Net Assets
Net proceeds from capital contributions and withdrawals	$	70,109,792
Net unrealized depreciation (computed on the basis of identified cost)		(694,856	)
Total	$	69,414,936

Statement of Operations

For the Year Ended
October 31, 2008

Investment Income
Dividends	$	1,249,040
Interest		11,760
Total investment income	$	1,260,800
Expenses
Investment adviser fee	$	756,324
Trustees' fees and expenses		5,513
Custodian fee		68,888
Legal and accounting services		24,085
Miscellaneous		3,295
Total expenses	$	858,105
Deduct — Reduction of investment adviser fee	$	11,693
Total expense reductions	$	11,693
Net expenses	$	846,412
Net investment income	$	414,388
Realized and Unrealized Gain (Loss)
Net realized gain (loss) — Investment transactions (identified cost basis)	$	(1,072,222	)
Net realized loss	$	(1,072,222	)
Change in unrealized appreciation (depreciation) — Investments (identified cost basis)	$	(30,626,771	)
Net change in unrealized appreciation (depreciation)	$	(30,626,771	)
Net realized and unrealized loss	$	(31,698,993	)
Net decrease in net assets from operations	$	(31,284,605	)

See notes to financial statements
20

Tax-Managed Mid-Cap Core Portfolio as of October 31, 2008

FINANCIAL STATEMENTS CONT'D

Statements of Changes in Net Assets

Increase (Decrease) in Net Assets	Year Ended October 31, 2008			Year Ended October 31, 2007
From operations — Net investment income	$	414,388		$	431,454
Net realized gain (loss) from investment transactions		(1,072,222	)		8,082,328
Net change in unrealized appreciation (depreciation)   of investments		(30,626,771	)		8,326,667
Net increase (decrease) in net assets from operations	$	(31,284,605	)	$	16,840,449
Capital transactions — Contributions	$	5,183,135		$	8,454,067
Withdrawals		(14,648,201	)		(13,006,661	)
Net decrease in net assets from capital transactions	$	(9,465,066	)	$	(4,552,594	)
Net increase (decrease) in net assets	$	(40,749,671	)	$	12,287,855
Net Assets
At beginning of year	$	110,164,607		$	97,876,752
At end of year	$	69,414,936		$	110,164,607

See notes to financial statements
21

Tax-Managed Mid-Cap Core Portfolio as of October 31, 2008

FINANCIAL STATEMENTS CONT'D

Supplementary Data

	Year Ended October 31,
	2008			2007			2006			2005			2004
Ratios/Supplemental Data
Ratios (As a percentage of average daily net assets):
Expenses(1)		0.90	%		0.90	%		0.91	%		0.91	%		0.93	%
Net investment income (loss)		0.44	%		0.41	%		0.29	%		(0.11	)%		(0.15	)%
Portfolio Turnover		40	%		38	%		55	%		53	%		42	%
Total Return		(30.51	)%		17.79	%		13.85	%		10.54	%		6.43	%
Net assets, end of year (000's omitted)	$	69,415		$	110,165		$	97,877		$	76,091		$	67,130

⁽¹⁾  The investment adviser waived a portion of its investment adviser fee (equal to 0.01% for the year ended October 31, 2008 and less than 0.01% of average daily net assets for each of the years ended October 31, 2007, 2006, 2005 and 2004). A portion of the waiver was borne by the sub-adviser.

See notes to financial statements
22

Tax-Managed Mid-Cap Core Portfolio as of October 31, 2008

NOTES TO FINANCIAL STATEMENTS

1  Significant Accounting Policies

Tax-Managed Mid-Cap Core Portfolio (the Portfolio) is a New York trust registered under the Investment Company Act of 1940, as amended (the 1940 Act), as a diversified, open-end management investment company. The Portfolio's investment objective is to achieve long-term, after-tax returns by investing in a diversified portfolio of common stocks of mid-cap companies. The Declaration of Trust permits the Trustees to issue interests in the Portfolio. At October 31, 2008, Eaton Vance Tax-Managed Mid-Cap Core Fund and Eaton Vance Tax-Managed Equity Asset Allocation Fund held an interest of 35.7% and 64.3%, respectively, in the Portfolio.

The following is a summary of significant accounting policies of the Portfolio. The policies are in conformity with accounting principles generally accepted in the United States of America.

A  Investment Valuation — Equity securities listed on a U.S. securities exchange generally are valued at the last sale price on the day of valuation or, if no sales took place on such date, at the mean between the closing bid and asked prices therefore on the exchange where such securities are principally traded. Equity securities listed on the NASDAQ Global or Global Select Market generally are valued at the NASDAQ official closing price. Unlisted or listed securities for which closing sales prices or closing quotations are not available are valued at the mean between the latest available bid and asked prices or, in the case of preferred equity securities that are not listed or traded in the over-the-counter market, by an independent pricing service. Short-term debt secur ities with a remaining maturity of sixty days or less are valued at amortized cost, which approximates market value. If short-term debt securities are acquired with a remaining maturity of more than sixty days, they will be valued by a pricing service. Investments for which valuations or market quotations are not readily available are valued at fair value using methods determined in good faith by or at the direction of the Trustees of the Portfolio considering relevant factors, data and information including the market value of freely tradable securities of the same class in the principal market on which such securities are normally traded.

B  Investment Transactions — Investment transactions for financial statement purposes are accounted for on a trade date basis. Realized gains and losses on investments sold are determined on the basis of identified cost.

C  Income — Dividend income is recorded on the ex-dividend date for dividends received in cash and/or securities.

D  Federal Taxes — The Portfolio has elected to be treated as a partnership for federal tax purposes. No provision is made by the Portfolio for federal or state taxes on any taxable income of the Portfolio because each investor in the Portfolio is ultimately responsible for the payment of any taxes on its share of taxable income. Since at least one of the Portfolio's investors is a regulated investment company that invests all or substantially all of its assets in the Portfolio, the Portfolio normally must satisfy the applicable source of income and diversification requirements (under the Internal Revenue Code) in order for its investors to satisfy them. The Portfolio will allocate, at least annually among its investors, each investor's distributive share of the Portfolio' s net investment income, net realized capital gains and any other items of income, gain, loss, deduction or credit.

As of October 31, 2008, the Portfolio had no uncertain tax positions that would require financial statement recognition, de-recognition, or disclosure. Each of the Portfolio's federal tax returns filed in the 3-year period ended October 31, 2008 remains subject to examination by the Internal Revenue Service.

E  Expense Reduction — State Street Bank and Trust Company (SSBT) serves as custodian of the Portfolio. Pursuant to the custodian agreement, SSBT receives a fee reduced by credits, which are determined based on the average daily cash balance the Portfolio maintains with SSBT. All credit balances, if any, used to reduce the Portfolio's custodian fees are reported as a reduction of expenses in the Statement of Operations.

F  Use of Estimates — The preparation of the financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and the reported amounts of income and expense during the reporting period. Actual results could differ from those estimates.

G  Indemnifications — Under the Portfolio's organizational documents, its officers and Trustees may be indemnified against certain liabilities and expenses arising out of the performance of their duties to the Portfolio. Interestholders in the Portfolio are jointly and severally liable for the liabilities and obligations of the Portfolio in the event that the Portfolio fails to satisfy such liabilities and obligations; provided, however, that, to the extent assets are available in the Portfolio, the Portfolio may, under certain circumstances, indemnify interestholders from and against any claim or liability to which such holder may become

23

Tax-Managed Mid-Cap Core Portfolio as of October 31, 2008

NOTES TO FINANCIAL STATEMENTS CONT'D

subject by reason of being or having been an interestholder in the Portfolio. Additionally, in the normal course of business, the Portfolio enters into agreements with service providers that may contain indemnification clauses. The Portfolio's maximum exposure under these arrangements is unknown as this would involve future claims that may be made against the Portfolio that have not yet occurred.

2  Investment Adviser Fee and Other Transactions with Affiliates

The investment adviser fee is earned by Boston Management and Research (BMR), a subsidiary of Eaton Vance Management (EVM), as compensation for management and investment advisory services rendered to the Portfolio. The fee is computed at an annual rate of 0.80% of the Portfolio's average daily net assets up to $500 million and at reduced rates as daily net assets exceed that level, and is payable monthly. Pursuant to a sub-advisory agreement, BMR pays Atlanta Capital Management Company LLC (Atlanta Capital), an affiliate of EVM, a portion of its advisory fee for sub-advisory services provided to the Portfolio. For the year ended October 31, 2008, the adviser fee was 0.80% of the Portfolio's average daily net assets and amounted to $756,324. BMR has also agreed to reduce the investment adviser fee by an amount equal to that portion of commissions paid to broker dealers in execution of security transactions attributed to the Portf olio that is consideration for third-party research services. For the year ended October 31, 2008, BMR waived $11,693 of its adviser fee. Atlanta Capital, in turn, waived $11,693 of its sub-adviser fee.

Except for Trustees of the Portfolio who are not members of EVM's or BMR's organizations, officers and Trustees receive remuneration for their services to the Portfolio out of the investment adviser fee. Trustees of the Portfolio who are not affiliated with the investment adviser may elect to defer receipt of all or a percentage of their annual fees in accordance with the terms of the Trustees Deferred Compensation Plan. For the year ended October 31, 2008, no significant amounts have been deferred. Certain officers and Trustees of the Portfolio are officers of the above organizations.

3  Purchases and Sales of Investments

Purchases and sales of investments, other than short-term obligations, aggregated $37,555,699 and $47,870,507, respectively, for the year ended October 31, 2008.

4  Federal Income Tax Basis of Investments

The cost and unrealized appreciation (depreciation) of investments of the Portfolio at October 31, 2008, as determined on a federal income tax basis, were as follows:

Aggregate cost	$	69,224,044
Gross unrealized appreciation	$	7,502,482
Gross unrealized depreciation		(8,260,765	)
Net unrealized depreciation	$	(758,283	)

5  Line of Credit

The Portfolio participates with other portfolios and funds managed by EVM and its affiliates in a $450 million unsecured line of credit agreement with a group of banks. Borrowings are made by the Portfolio solely to facilitate the handling of unusual and/or unanticipated short-term cash requirements. Interest is charged to the Portfolio based on its borrowings at an amount above either the Eurodollar rate or Federal Funds rate. In addition, a fee computed at an annual rate of 0.10% on the daily unused portion of the line of credit is allocated among the participating portfolios and funds at the end of each quarter. The Portfolio did not have any significant borrowings or allocated fees during the year ended October 31, 2008.

6  Recently Issued Accounting Pronouncement

In September 2006, the Financial Accounting Standards Board issued Statement of Financial Accounting Standards No. 157 (FAS 157), "Fair Value Measurements". FAS 157 defines fair value, establishes a framework for measuring fair value in accordance with accounting principles generally accepted in the United States of America and expands disclosure about fair value measurements. FAS 157 is effective for fiscal years beginning after November 15, 2007. As of October 31, 2008, management does not believe the adoption of FAS 157 will impact the amounts reported in the financial statements; however, additional disclosures may be required about the inputs used to develop the measurements of fair value and the effect of certain of the measurements on changes in net assets for the period.

24

Tax-Managed Mid-Cap Core Portfolio as of October 31, 2008

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Trustees and Investors of
Tax-Managed Mid-Cap Core Portfolio:

We have audited the accompanying statement of assets and liabilities including the portfolio of investments, of Tax-Managed Mid-Cap Core Portfolio (the "Portfolio"), as of October 31, 2008, and the related statement of operations for the year then ended, the statements of changes in net assets for each of the two years in the period then ended, and the supplementary data for each of the five years in the period then ended. These financial statements and supplementary data are the responsibility of the Portfolio's management. Our responsibility is to express an opinion on these financial statements and supplementary data based on our audits.

We conducted our audits in accordance with standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements and supplementary data are free of material misstatement. The Portfolio is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. Our audits included consideration of internal control over financial reporting as a basis for designing audit procedures that are appropriate in the circumstances, but not for the purpose of expressing an opinion on the effectiveness of the Portfolio's internal control over financial reporting. Accordingly, we express no such opinion. An audit also includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, as well as evaluating the overall financial statement presentation. Our procedures included confirmation of securities owned as of October 31, 2008, by correspondence with the custodian. We believe that our audits provide a reasonable basis for our opinion.

In our opinion, the financial statements and supplementary data referred to above present fairly, in all material respects, the financial position of Tax-Managed Mid-Cap Core Portfolio as of October 31, 2008, the results of its operations for the year then ended, the changes in its net assets for each of the two years in the period then ended, and the supplementary data for each of the five years in the period then ended, in conformity with accounting principles generally accepted in the United States of America.

DELOITTE & TOUCHE LLP
Boston, Massachusetts
December 15, 2008

25

Eaton Vance Tax-Managed Mid-Cap Core Fund
Tax-Managed Mid-Cap Core Portfolio

SPECIAL MEETING OF SHAREHOLDERS (Unaudited)

Eaton Vance Tax-Managed Mid-Cap Core Fund

The Fund held a Special Meeting of Shareholders on November 14, 2008 to elect Trustees. The results of the vote were as follows:

	Number of Shares
Nominee for Trustee	For		Withheld
Benjamin C. Esty		2,040,828		1,428
Thomas E. Faust Jr.		2,040,828		1,428
Allen R. Freedman		2,040,828		1,428
William H. Park		2,039,499		2,757
Ronald A. Pearlman		2,040,828		1,428
Helen Frame Peters		2,040,828		1,428
Heidi L. Steiger		2,040,828		1,428
Lynn A. Stout		2,039,499		2,757
Ralph F. Verni		2,039,728		2,527

Each nominee was also elected a Trustee of the Portfolio.

Tax-Managed Mid-Cap Core Portfolio

The Portfolio held a Special Meeting of Interestholders on November 14, 2008 to elect Trustees. The results of the vote were as follows:

	Interest in the Portfolio
Nominee for Trustee	For			Withheld
Benjamin C. Esty		99	%		1	%
Thomas E. Faust Jr.		99	%		1	%
Allen R. Freedman		99	%		1	%
William H. Park		99	%		1	%
Ronald A. Pearlman		99	%		1	%
Helen Frame Peters		99	%		1	%
Heidi L. Steiger		99	%		1	%
Lynn A. Stout		99	%		1	%
Ralph F. Verni		99	%		1	%

Results are rounded to the nearest whole number.

26

Eaton Vance Tax-Managed Mid-Cap Core Fund

BOARD OF TRUSTEES' ANNUAL APPROVAL OF THE INVESTMENT ADVISORY AGREEMENT

Overview of the Contract Review Process

The Investment Company Act of 1940, as amended (the "1940 Act"), provides, in substance, that each investment advisory agreement between a fund and its investment adviser will continue in effect from year to year only if its continuance is approved at least annually by the fund's board of trustees, including by a vote of a majority of the trustees who are not "interested persons" of the fund ("Independent Trustees"), cast in person at a meeting called for the purpose of considering such approval.

At a meeting of the Boards of Trustees (each a "Board") of the Eaton Vance group of mutual funds (the "Eaton Vance Funds") held on April 21, 2008, the Board, including a majority of the Independent Trustees, voted to approve continuation of existing advisory and sub-advisory agreements for the Eaton Vance Funds for an additional one-year period. In voting its approval, the Board relied upon the affirmative recommendation of the Contract Review Committee of the Board (formerly the Special Committee), which is a committee comprised exclusively of Independent Trustees. Prior to making its recommendation, the Contract Review Committee reviewed information furnished for a series of meetings of the Contract Review Committee held in February, March and April 2008. Such information included, among other things, the following:

Information about Fees, Performance and Expenses

•  An independent report comparing the advisory and related fees paid by each fund with fees paid by comparable funds;

•  An independent report comparing each fund's total expense ratio and its components to comparable funds;

•  An independent report comparing the investment performance of each fund to the investment performance of comparable funds over various time periods;

•  Data regarding investment performance in comparison to relevant peer groups of funds and appropriate indices;

•  Comparative information concerning fees charged by each adviser for managing other mutual funds and institutional accounts using investment strategies and techniques similar to those used in managing the fund;

•  Profitability analyses for each adviser with respect to each fund;

Information about Portfolio Management

•  Descriptions of the investment management services provided to each fund, including the investment strategies and processes employed, and any changes in portfolio management processes and personnel;

•  Information concerning the allocation of brokerage and the benefits received by each adviser as a result of brokerage allocation, including information concerning the acquisition of research through "soft dollar" benefits received in connection with the funds' brokerage, and the implementation of a soft dollar reimbursement program established with respect to the funds;

•  Data relating to portfolio turnover rates of each fund;

•  The procedures and processes used to determine the fair value of fund assets and actions taken to monitor and test the effectiveness of such procedures and processes;

Information about each Adviser

•  Reports detailing the financial results and condition of each adviser;

•  Descriptions of the qualifications, education and experience of the individual investment professionals whose responsibilities include portfolio management and investment research for the funds, and information relating to their compensation and responsibilities with respect to managing other mutual funds and investment accounts;

•  Copies of the Codes of Ethics of each adviser and its affiliates, together with information relating to compliance with and the administration of such codes;

•  Copies of or descriptions of each adviser's proxy voting policies and procedures;

•  Information concerning the resources devoted to compliance efforts undertaken by each adviser and its affiliates on behalf of the funds (including descriptions of various compliance programs) and their record of compliance with investment policies and restrictions, including policies with respect to market-timing, late trading and selective portfolio disclosure, and with policies on personal securities transactions;

•  Descriptions of the business continuity and disaster recovery plans of each adviser and its affiliates;

27

Eaton Vance Tax-Managed Mid-Cap Core Fund

BOARD OF TRUSTEES' ANNUAL APPROVAL OF THE INVESTMENT ADVISORY AGREEMENT CONT'D

Other Relevant Information

•  Information concerning the nature, cost and character of the administrative and other non-investment management services provided by Eaton Vance Management and its affiliates;

•  Information concerning management of the relationship with the custodian, subcustodians and fund accountants by each adviser or the funds' administrator; and

•  The terms of each advisory agreement.

In addition to the information identified above, the Contract Review Committee considered information provided from time to time by each adviser throughout the year at meetings of the Board and its committees. Over the course of the twelve-month period ended April 30, 2008, the Board met eleven times and the Contract Review Committee, the Audit Committee and the Governance Committee, each of which is a Committee comprised solely of Independent Trustees, met twelve, seven and five times, respectively. At such meetings, the Trustees received, among other things, presentations by the portfolio managers and other investment professionals of each adviser relating to the investment performance of each fund and the investment strategies used in pursuing the fund's investment objective. The Portfolio Management Committee and the Compliance Reports and Regulatory Matters Committee are newly established and did not meet during the twelve- month period ended April 30, 2008.

For funds that invest through one or more underlying portfolios, the Board considered similar information about the portfolio(s) when considering the approval of advisory agreements. In addition, in cases where the fund's investment adviser has engaged a sub-adviser, the Board considered similar information about the sub-adviser when considering the approval of any sub-advisory agreement.

The Contract Review Committee was assisted throughout the contract review process by Goodwin Procter LLP, legal counsel for the Independent Trustees. The members of the Contract Review Committee relied upon the advice of such counsel and their own business judgment in determining the material factors to be considered in evaluating each advisory and sub-advisory agreement and the weight to be given to each such factor. The conclusions reached with respect to each advisory and sub-advisory agreement were based on a comprehensive evaluation of all the information provided and not any single factor. Moreover, each member of the Contract Review Committee may have placed varying emphasis on particular factors in reaching conclusions with respect to each advisory and sub-advisory agreement.

Results of the Process

Based on its consideration of the foregoing, and such other information as it deemed relevant, including the factors and conclusions described below, the Contract Review Committee concluded that the continuance of the investment advisory agreement of the Tax-Managed Mid-Cap Core Portfolio (the "Portfolio"), the portfolio in which the Eaton Vance Tax-Managed Mid-Cap Core Fund (the "Fund") invests, with Boston Management and Research (the "Adviser"), and the sub-advisory agreement with Atlanta Capital Management Company, LLC (the "Sub-adviser"), including their fee structures, is in the interests of shareholders and, therefore, the Contract Review Committee recommended to the Board approval of the respective agreements. The Board accepted the recommendation of the Contract Review Committee as well as the factors considered and conclusions reached by the Contract Review Committee with respect to the agreements. Accordingly, the Boa rd, including a majority of the Independent Trustees, voted to approve continuation of the investment advisory agreement and sub-advisory agreement for the Portfolio.

Nature, Extent and Quality of Services

In considering whether to approve the investment advisory agreement and sub-advisory agreements of the Portfolio, the Board evaluated the nature, extent and quality of services provided to the Portfolio by the Adviser and the Sub-adviser.

The Board considered the Adviser's and the Sub-adviser's management capabilities and investment process with respect to the types of investments held by the Portfolio, including the education, experience and number of its investment professionals and other personnel who provide portfolio management, investment research, and similar services to the Portfolio and whose responsibilities include supervising the Sub-adviser. The Board specifically noted the Adviser's in-house equity research capabilities. The Board also took into account the resources dedicated to portfolio management and other services, including the compensation paid to recruit and retain investment personnel, and the time and attention devoted to the Portfolio by senior management. With respect to the Sub-adviser, the Board took into account the resources available to the Sub-adviser in fulfilling its duties under the sub-advisory agreement and the Sub-adviser's e xperience in managing equity portfolios.

The Board also reviewed the compliance programs of the Adviser and relevant affiliates thereof, including the Sub-adviser. Among other matters, the Board considered compliance and reporting matters relating to personal trading by investment personnel, selective disclosure of portfolio holdings, late trading, frequent trading, portfolio valuation, business continuity and the allocation of investment

28

Eaton Vance Tax-Managed Mid-Cap Core Fund

BOARD OF TRUSTEES' ANNUAL APPROVAL OF THE INVESTMENT ADVISORY AGREEMENT CONT'D

opportunities. The Board also evaluated the responses of the Adviser and its affiliates to requests from regulatory authorities such as the Securities and Exchange Commission.

The Board also considered shareholder and other administrative services provided or managed by Eaton Vance Management and its affiliates, including transfer agency and accounting services. The Board evaluated the benefits to shareholders of investing in a fund that is a part of a large family of funds, including the ability, in many cases, to exchange an investment among different funds without incurring additional sales charges.

After consideration of the foregoing factors, among others, the Board concluded that the nature, extent and quality of services provided by the Adviser and Sub-adviser, taken as a whole, are appropriate and consistent with the terms of the investment advisory agreement and sub-advisory agreement, respectively.

Fund Performance

The Board compared the Fund's investment performance to a relevant universe of similarly managed funds identified by an independent data provider and appropriate benchmark indices. The Board reviewed comparative performance data for the one-, three- and five-year periods ended September 30, 2007 for the Fund. The Board noted that action was taken during 2006 and 2007 to improve the performance of the Fund and concluded that such actions were effective in improving the Fund's performance since that time.

Management Fees and Expenses

The Board reviewed contractual investment advisory fee rates, including any administrative fee rates, payable by the Portfolio and the Fund (referred to collectively as "management fees"). As part of its review, the Board considered the management fees (including administrative fees) and the Fund's total expense ratio for the year ended September 30, 2007, as compared to a group of similarly managed funds selected by an independent data provider. The Board considered the fact that the Administrator waived fees and/or paid expenses for the Fund and had agreed to waive fees and/or pay expenses in an additional amount for the next two years.

After reviewing the foregoing information, and in light of the nature, extent and quality of the services provided by the Adviser, the Board concluded that the management fees charged for advisory and related services and the Fund's total expense ratio are reasonable.

Profitability

The Board reviewed the level of profits realized by the Adviser and relevant affiliates thereof, including the Sub-adviser, in providing investment advisory and administrative services to the Portfolio, the Fund and to all Eaton Vance Funds as a group. The Board considered the level of profits realized without regard to revenue sharing or other payments by the Adviser and its affiliates to third parties in respect of distribution services. The Board also considered other direct or indirect benefits received by the Adviser and its affiliates in connection with its relationship with the Portfolio and the Fund, including the benefits of research services that may be available to the Adviser or Sub-adviser as a result of securities transactions effected for the Portfolio and other advisory clients.

The Board concluded that, in light of the foregoing factors and the nature, extent and quality of the services rendered, the profits realized by the Adviser and its affiliates, including the Sub-adviser, are reasonable.

Economies of Scale

In reviewing management fees and profitability, the Board also considered the extent to which the Adviser and its affiliates, on the one hand, and the Fund, on the other hand, can expect to realize benefits from economies of scale as the assets of the Fund and the Portfolio increase. The Board acknowledged the difficulty in accurately measuring the benefits resulting from the economies of scale with respect to the management of any specific fund or group of funds. The Board reviewed data summarizing the increases and decreases in the assets of the Fund and of all Eaton Vance Funds as a group over various time periods, and evaluated the extent to which the total expense ratio of the Fund and the profitability of the Adviser and its affiliates may have been affected by such increases or decreases. Based upon the foregoing, the Board concluded that the benefits from economies of scale are currently being shared equitably by the Adv iser and its affiliates and the Fund. The Board also concluded that, assuming reasonably foreseeable increases in the assets of the Portfolio, the structure of the advisory fee, which includes breakpoints at several asset levels, can be expected to cause the Adviser and its affiliates and the Fund to continue to share such benefits equitably.

29

Eaton Vance Tax-Managed Mid-Cap Core Fund

MANAGEMENT AND ORGANIZATION

Fund Management. The Trustees of Eaton Vance Mutual Funds Trust (the Trust) and Tax-Managed Mid-Cap Core Portfolio (the Portfolio) are responsible for the overall management and supervision of the Trust's and Portfolio's affairs. The Trustees and officers of the Trust and the Portfolio are listed below. Except as indicated, each individual has held the office shown or other offices in the same company for the last five years. Trustees and officers of the Trust and the Portfolio hold indefinite terms of office. The "noninterested Trustees" consist of those Trustees who are not "interested persons" of the Trust and the Portfolio, as that term is defined under the 1940 Act. The business address of each Trustee and officer is The Eaton Vance Building, 255 State Street, Boston, Massachusetts 02109. As used below, "EVC" refers to Eaton Vance Corp., "EV" refers to Eaton Vance, Inc., "EVM" refers to Eaton Vance Management, "BMR" refers to Boston Management and Research, "Parametric" refers to Parametric Portfolio Associates, "EVD" refers to Eaton Vance Distributors, Inc. and "Atlanta Capital" refers to Atlanta Capital Management Company, LLC. EVC and EV are the corporate parent and trustee, respectively, of EVM and BMR. EVD is the Fund's principal underwriter, the Portfolio's placement agent and a wholly-owned subsidiary of EVC. Each officer affiliated with Eaton Vance may hold a position with other Eaton Vance affiliates that is comparable to his or her position with EVM listed below.

Date of Birth	Position(s) with the Name and the Portfolio	Term of Office and Trust and Service	Length of During Past Five Years	Number of Portfolios in Fund Complex Principal Occupation(s) Trustee(1)		Overseen By Other Directorships Held
Interested Trustee
Thomas E. Faust Jr. 5/31/58	Trustee of the Trust and Portfolio, President of the Trust and Vice President of the Portfolio	Trustee since 2007, President of the Trust since 2002 and Vice President of the Portfolio since 2001	Chairman, Chief Executive Officer and President of EVC, Director and President of EV, Chief Executive Officer and President of EVM and BMR, and Director of EVD. Trustee and/or Officer of 173 registered investment companies and 4 private companies managed by EVM or BMR. Mr. Faust is an interested person because of his positions with EVM, BMR, EVD, EVC and EV, which are affiliates of the Trust and Portfolio.		173	Director of EVC
Noninterested Trustees
Benjamin C. Esty 1/2/63	Trustee	Since 2005	Roy and Elizabeth Simmons Professor of Business Administration, Harvard University Graduate School of Business Administration.		173	None
Allen R. Freedman 4/3/40	Trustee	Since 2007	Former Chairman (2002-2004) and a Director (1983-2004) of Systems & Computer Technology Corp. (provider of software to higher education). Formerly, a Director of Loring Ward International (fund distributor) (2005-2007). Formerly, Chairman and a Director of Indus International Inc. (provider of enterprise management software to the power generating industry) (2005-2007).		173	Director of Assurant, Inc. and Stonemor Partners L.P. (owner and operator of cemeteries)
William H. Park 9/19/47	Trustee	Since 2003	Vice Chairman, Commercial Industrial Finance Corp. (specialty finance company) (since 2006). Formerly, President and Chief Executive Officer, Prizm Capital Management, LLC (investment management firm) (2002-2005).		173	None
Ronald A. Pearlman 7/10/40	Trustee	Since 2003	Professor of Law, Georgetown University Law Center.		173	None
Helen Frame Peters 3/22/48	Trustee	Since 2008	Professor of Finance, Carroll School of Management, Boston College (since 2003). Adjunct Professor of Finance, Peking University, Beijing, China (since 2005). Formerly, Dean, Carroll School of Management, Boston College (2000-2003).		173	Director of Federal Home Loan Bank of Boston (a bank for banks) and BJ's Wholesale Clubs (wholesale club retailer); Trustee of SPDR Index Shares Funds and SPDR Series Trust (exchange traded funds)

30

Eaton Vance Tax-Managed Mid-Cap Core Fund

MANAGEMENT AND ORGANIZATION CONT'D

Date of Birth	Position(s) with the Name and the Portfolio	Term of Office and Trust and Service	Length of During Past Five Years	Number of Portfolios in Fund Complex Principal Occupation(s) Trustee(1)		Overseen By Other Directorships Held
Noninterested Trustees (continued)
Heidi L. Steiger 7/8/53	Trustee	Since 2007	Managing Partner, Topridge Associates LLC (global wealth management firm) (since 2008); Senior Advisor (since 2008), President (2005-2008), Lowenhaupt Global Advisors, LLC (global wealth management firm). Formerly, President and Contributing Editor, Worth Magazine (2004-2005). Formerly, Executive Vice President and Global Head of Private Asset Management (and various other positions), Neuberger Berman (investment firm) (1986-2004).		173	Director of Nuclear Electric Insurance Ltd. (nuclear insurance provider) and Aviva USA (insurance provider)
Lynn A. Stout 9/14/57	Trustee	Of the Trust since 1998 and of the Portfolio since 2001	Paul Hastings Professor of Corporate and Securities Law (since 2006) and Professor of Law (2001-2006), University of California at Los Angeles School of Law.		173	None
Ralph F. Verni 1/26/43	Chairman of the Board and Trustee	Chairman of the Board since 2007 and Trustee since 2005	Consultant and private investor.		173	None

Principal Officers who are not Trustees
Name and Date of Birth	Position(s) with the Trust and the Portfolio	Term of Office and Length of Service	Principal Occupation(s) During Past Five Years
William H. Ahern, Jr. 7/28/59	Vice President of the Trust	Since 1995	Vice President of EVM and BMR. Officer of 75 registered investment companies managed by EVM or BMR.
John R. Baur 2/10/70	Vice President of the Trust	Since 2007	Vice President of EVM and BMR. Previously, attended Johnson Graduate School of Management, Cornell University (2002-2005), and prior thereto he was an Account Team Representative in Singapore for Applied Materials, Inc. Officer of 33 registered investment companies managed by EVM or BMR.
William O. Bell, IV 7/26/73	Vice President of the Portfolio	Since 2005	Vice President of Atlanta Capital. Officer of 2 registered investment companies managed by EVM or BMR.
Michael A. Cirami 12/24/75	Vice President of the Trust	Since 2007	Vice President of EVM and BMR. Previously, attended the University of Rochester William E. Simon Graduate School of Business Administration (2001-2003), and prior thereto he was a Team Leader for the Institutional Services Group for State Street Bank in Luxembourg. Officer of 33 registered investment companies managed by EVM or BMR.
Cynthia J. Clemson 3/2/63	Vice President of the Trust	Since 2005	Vice President of EVM and BMR. Officer of 90 registered investment companies managed by EVM or BMR.
Charles B. Gaffney 12/4/72	Vice President of the Trust	Since 2007	Vice President of EVM and BMR. Previously, Sector Portfolio Manager and Senior Equity Analyst of Brown Brothers Harriman (1997-2003). Officer of 30 registered investment companies managed by EVM or BMR.
William R. Hackney, III 4/12/48	Vice President of the Portfolio	Since 2001	Managing Partner and member of the Executive Committee of Atlanta Capital. Officer of 2 registered investment companies managed by EVM or BMR.
Marilyn Robinson Irvin 6/17/58	Vice President of the Portfolio	Since 2005	Senior Vice President and Principal of Atlanta Capital. Officer of 2 registered investment companies managed by EVM or BMR.
Christine M. Johnston 11/9/72	Vice President of the Trust	Since 2007	Vice President of EVM and BMR. Officer of 35 registered investment companies managed by EVM or BMR.

31

Eaton Vance Tax-Managed Mid-Cap Core Fund

MANAGEMENT AND ORGANIZATION CONT'D

Name and Date of Birth	Position(s) with the Trust and the Portfolio	Term of Office and Length of Service	Principal Occupation(s) During Past Five Years
Principal Officers who are not Trustees (continued)
Aamer Khan 6/7/60	Vice President of the Trust	Since 2005	Vice President of EVM and BMR. Officer of 33 registered investment companies managed by EVM or BMR.
Thomas H. Luster 4/8/62	Vice President of the Trust	Since 2006	Vice President of EVM and BMR. Officer of 51 registered investment companies managed by EVM or BMR.
Robert B. MacIntosh 1/22/57	Vice President of the Trust	Since 1998	Vice President of EVM and BMR. Officer of 90 registered investment companies managed by EVM or BMR.
Duncan W. Richardson 10/26/57	Vice President of the Trust and President of the Portfolio	Vice President of the Trust since 2001 and President of the Portfolio since 2007	Executive Vice President and Chief Equity Investment Officer of EVC, EVM and BMR. Officer of 81 registered investment companies managed by EVM or BMR.
Judith A. Saryan 8/21/54	Vice President of the Trust	Since 2003	Vice President of EVM and BMR. Officer of 55 registered investment companies managed by EVM or BMR.
Susan Schiff 3/13/61	Vice President of the Trust	Since 2002	Vice President of EVM and BMR. Officer of 36 registered investment companies managed by EVM or BMR.
Thomas Seto 9/27/62	Vice President of the Trust	Since 2007	Vice President and Director of Portfolio Management of Parametric. Officer of 31 registered investment companies managed by EVM or BMR.
David M. Stein 5/4/51	Vice President of the Trust	Since 2007	Managing Director and Chief Investment Officer of Parametric. Officer of 31 registered investment companies managed by EVM or BMR.
Mark S. Venezia 5/23/49	Vice President of the Trust	Since 2007	Vice President of EVM and BMR. Officer of 36 registered investment companies managed by EVM or BMR.
Adam A. Weigold 3/22/75	Vice President of the Trust	Since 2007	Vice President of EVM and BMR. Officer of 71 registered investment companies managed by EVM or BMR.
Barbara E. Campbell 6/19/57	Treasurer	Of the Trust since 2005 and of the Portfolio since 2008(2)	Vice President of EVM and BMR. Officer of 173 registered investment companies managed by EVM or BMR.
Maureen A. Gemma 5/24/60	Secretary and Chief Legal Officer	Secretary since 2007 and Chief Legal Officer since 2008	Vice President of EVM and BMR. Officer of 173 registered investment companies managed by EVM or BMR.
Paul M. O'Neil 7/11/53	Chief Compliance Officer	Since 2004	Vice President of EVM and BMR. Officer of 173 registered investment companies managed by EVM or BMR.

⁽¹⁾  Includes both master and feeder funds in a master-feeder structure.

⁽²⁾  Prior to 2008, Ms. Campbell served as Assistant Treasurer of the Portfolio since 2001.

The SAI for the Fund includes additional information about the Trustees and officers of the Fund and the Portfolio and can be obtained without charge on Eaton Vance's website at www.eatonvance.com or by calling 1-800-262-1122.

32

Investment Adviser of Tax-Managed Mid-Cap Core Portfolio
Boston Management and Research

The Eaton Vance Building
255 State Street
Boston, MA 02109

Sub-Adviser of Tax-Managed Mid-Cap Core Portfolio
Atlanta Capital Management Company LLC

1349 West Peachtree Street
Suite 1600
Atlanta, GA 30309

Administrator of Eaton Vance Tax-Managed Mid-Cap Core Fund
Eaton Vance Management

The Eaton Vance Building
255 State Street
Boston, MA 02109

Principal Underwriter
Eaton Vance Distributors, Inc.

The Eaton Vance Building
255 State Street
Boston, MA 02109
(617) 482-8260

Custodian
State Street Bank and Trust Company

200 Clarendon Street
Boston, MA 02116

Transfer Agent
PNC Global Investing Services

Attn: Eaton Vance Funds
P.O. Box 9653
Providence, RI 02940-9653
(800) 262-1122

Independent Registered Public Accounting Firm
Deloitte & Touche LLP

200 Berkeley Street
Boston, MA 02116-5022

Eaton Vance Tax-Managed Mid-Cap Core Fund
The Eaton Vance Building
255 State Street
Boston, MA 02109

This report must be preceded or accompanied by a current prospectus. Before investing, investors should consider carefully the Fund's investment
objective, risks, and charges and expenses. The Fund's current prospectus contains this and other information about the Fund and is available
through your financial advisor. Please read the prospectus carefully before you invest or send money. For further information please call 1-800-262-1122.

1301-12/08  TMMCCSRC

Item 2. Code of Ethics

The registrant has adopted a code of ethics applicable to its Principal Executive Officer, Principal Financial Officer and Principal Accounting Officer.  The registrant undertakes to provide a copy of such code of ethics to any person upon request, without charge, by calling 1-800-262-1122.

Item 3. Audit Committee Financial Expert

The registrant’s Board has designated William H. Park, an independent trustee, as its audit committee financial expert.  Mr. Park is a certified public accountant who is the Vice Chairman of Commercial Industrial Finance Corp (specialty finance company). Previously, he served as President and Chief Executive Officer of Prizm Capital Management, LLC (investment management firm) and as Executive Vice President and Chief Financial Officer of United Asset Management Corporation (“UAM”) (a holding company owning institutional investment management firms).

Item 4. Principal Accountant Fees and Services

(a)-(d)

The following table presents the aggregate fees billed to the registrant for the fiscal period from inception to October 31, 2007 and the fiscal year ended October 31, 2008 by the registrant’s principal accountant for professional services rendered for the audit of the registrant’s annual financial statements and fees billed for other services rendered by the principal accountant during those periods.

Fiscal Years Ended	10/31/2007		10/31/2008
Audit Fees	$	23,790	$	22,655
Audit-Related Fees(1)	$	0	$	0
Tax Fees(2)	$	5,961	$	6,170
All Other Fees(3)	$	0	$	91
Total	$	29,751	$	28,916

(1)Audit-related fees consist of the aggregate fees billed for assurance and related services that are reasonably related to the performance of the audit of the registrant’s financial statements and are not reported under the category of audit fees.

(2)Tax fees consist of the aggregate fees billed for professional services rendered by the principal accountant relating to tax compliance, tax advice, and tax planning and specifically include fees for tax return preparation and other tax related compliance/planning matters.

(3)All other fees consist of the aggregate fees billed for products and services provided by the registrant’s principal accountant other than audit, audit-related, and tax services.

For the fiscal years ended October 31, 2007 and October 31, 2008, the registrant was billed $35,000 and $40,000, respectively, by D&T the principal accountant for the registrant, for work done in connection with its Rule 17Ad-13 examination of Eaton Vance Management’s assertion that it has maintained an effective internal control structure over sub-transfer agent and registrar functions, such services being pre-approved in accordance with Rule 2-01(c)(7)(ii) of Regulation S-X.

(e)(1) The registrant’s audit committee has adopted policies and procedures relating to the pre-approval of services provided by the registrant’s principal accountant (the “Pre-Approval Policies”).  The Pre-Approval Policies establish a framework intended to assist the audit committee in the proper discharge of its pre-approval responsibilities.  As a general matter, the Pre-Approval Policies (i) specify certain types of audit, audit-related, tax, and other services determined to be pre-approved by the audit committee; and (ii) delineate specific procedures governing the mechanics of the pre-approval process, including the approval and monitoring of audit and non-audit service fees.  Unless a service is specifically pre-approved under the Pre-Approval Policies, it must be separately pre-approved by the audit committee.

The Pre-Approval Policies and the types of audit and non-audit services pre-approved therein must be reviewed and ratified by the registrant’s audit committee at least annually.  The registrant’s audit committee maintains full responsibility for the appointment, compensation, and oversight of the work of the registrant’s principal accountant.

(e)(2) No services described in paragraphs (b)-(d) above were approved by the registrant’s audit committee pursuant to the “de minimis exception” set forth in Rule 2-01 (c)(7)(i)(C) of Regulation S-X.

(f) Not applicable.

(g) The following table presents (i) the aggregate non-audit fees (i.e., fees for audit-related, tax, and other services) billed to the registrant by the registrant’s principal accountant for the registrant’s fiscal years ended October 31, 2007 and October 31, 2008; and (ii) the aggregate non-audit fees (i.e., fees for audit related, tax, and other services) billed to the Eaton Vance organization by the registrant’s principal accountant for the same time periods.

Fiscal Years Ended	10/31/2007		10/31/2008
Registrant	$	5,961	$	6,261
Eaton Vance(1)	$	286,446	$	317,301

(1)Certain subsidiaries of Eaton Vance Corp. provide ongoing services to the registrant.

(h) The registrant’s audit committee has considered whether the provision by the registrant’s principal accountant of non-audit services to the registrant’s investment adviser and any entity controlling, controlled by, or under common control with the adviser that provides ongoing services to the registrant that were not pre-approved pursuant to Rule 2-01(c)(7)(ii) of Regulation S-X is compatible with maintaining the principal accountant’s independence.

Item 5.  Audit Committee of Listed registrants

Not required in this filing.

Item 6. Schedule of Investments

Please see schedule of investments contained in the Report to Stockholders included under Item 1 of this Form N-CSR.

Item 7. Disclosure of Proxy Voting Policies and Procedures for Closed-End Management Investment Companies

Not required in this filing.

Item 8. Portfolio Managers of Closed-End Management Investment Companies

Not required in this filing.

Item 9. Purchases of Equity Securities by Closed-End Management Investment Company and Affiliated Purchasers.

Not required in this filing.

Item 10.  Submission of Matters to a Vote of Security Holders.

No Material Changes

Item 11. Controls and Procedures

(a) It is the conclusion of the registrant’s principal executive officer and principal financial officer that the effectiveness of the registrant’s current disclosure controls and procedures (such disclosure controls and procedures having been evaluated within 90 days of the date of this filing) provide reasonable assurance that the information required to be disclosed by the registrant has been recorded, processed, summarized and reported within the time period specified in the Commission’s rules and forms and that the information required to be disclosed by the registrant has been accumulated and communicated to the registrant’s principal executive officer and principal financial officer in order to allow timely decisions regarding required disclosure.

(b) There have been no changes in the registrant’s internal controls over financial reporting during the second fiscal quarter of the period covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting.

Item 12. Exhibits

(a)(1)	Registrant’s Code of Ethics - Not applicable (please see Item 2).
(a)(2)(i)	Treasurer’s Section 302 certification.
(a)(2)(ii)	President’s Section 302 certification.
(b)	Combined Section 906 certification.

Signatures

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Tax-Managed Mid-Cap Core Portfolio

By:	/s/ Duncan W. Richardson
	Duncan W. Richardson
	President
	December 15, 2008

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

By:	/s/ Barbara E. Campbell
	Barbara E. Campbell
	Treasurer
	December 15, 2008

By:	/s/ Duncan W. Richardson
	Duncan W. Richardson
	President
	December 15, 2008

EX-99.CERT

Exhibit 99.CERT

Tax-Managed Mid-Cap Core Portfolio

FORM N-CSR

Exhibit 12(a)(2)(i)

CERTIFICATION

I, Barbara E. Campbell; certify that:

1.I have reviewed this report on Form N-CSR of Tax-Managed Mid-Cap Core Portfolio;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations, changes in net assets, and cash flows (if the financial statements are required to include a statement of cash flows) of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940) and internal control over financial reporting (as defined in Rule 30a-3(d) under the Investment Company Act of 1940) for the registrant and have:

(a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of a date within 90 days prior to the filing date of this report based on such evaluation; and

(d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s second fiscal quarter of the period covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer(s) and I have disclosed to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

(a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize, and report financial information; and

(b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

December 15, 2008
	/s/ Barbara E. Campbell
	Barbara E. Campbell
	Treasurer

Tax-Managed Mid-Cap Core Portfolio

FORM N-CSR

Exhibit 12(a)(2)(ii)

CERTIFICATION

I, Duncan W. Richardson; certify that:

1.I have reviewed this report on Form N-CSR of Tax-Managed Mid-Cap Core Portfolio;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations, changes in net assets, and cash flows (if the financial statements are required to include a statement of cash flows) of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940) and internal control over financial reporting (as defined in Rule 30a-3(d) under the Investment Company Act of 1940) for the registrant and have:

(a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of a date within 90 days prior to the filing date of this report based on such evaluation; and

(d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s second fiscal quarter of the period covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer(s) and I have disclosed to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

(a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize, and report financial information; and

(b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

December 15, 2008
	/s/ Duncan W. Richardson
	Duncan W. Richardson
	President

EX-99.906CERT

Exhibit 99.906CERT

Form N-CSR Item 12(b) Exhibit

CERTIFICATION PURSUANT TO
18 U.S.C. SECTION 1350,
AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

The undersigned hereby certify in their capacity as Treasurer and President, respectively, of Tax-Managed Mid-Cap Core Portfolio(the “Portfolio”) that:

(a)the Annual Report of the Portfolio on Form N-CSR for the period ended October 31, 2008 (the “Report”) fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and

(b)the information contained in the Report fairly presents, in all material respects, the financial condition and the results of operations of the Portfolio for such period.

A signed original of this written statement required by section 906 has been provided to the Portfolio and will be retained by the Portfolio and furnished to the Securities and Exchange Commission or its staff upon request.

Tax-Managed Mid-Cap Core Portfolio

December 15, 2008

/s/ Barbara E. Campbell

Barbara E. Campbell

Treasurer

December 15, 2008

/s/ Duncan W. Richardson

Duncan W. Richardson

President