Summary Prospectus
February 1, 2017

Loomis Sayles Small Cap Growth Fund

Ticker Symbol: Retail Class (LCGRX), Institutional Class (LSSIX), Class N (LSSNX)

Before you invest, you may want to review the Fund's Prospectus, which contains more information about the Fund and its risks. You can find the Fund's Prospectus and other information about the Fund online at www.loomissayles.com/Prospectus. You can also get this information at no cost by calling 800-633-3330 or by sending an e-mail request to FundInformation@loomissayles.com. The Fund's Prospectus and Statement of Additional Information ("SAI"), each dated February 1, 2017, as may be revised or supplemented from time to time, are incorporated by reference into this Summary Prospectus.

INVESTMENT OBJECTIVE

The Fund's investment objective is long-term capital growth from investments in common stocks or other equity securities.

FUND FEES & EXPENSES

The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

The Fund does not impose a sales charge, a redemption fee or an exchange fee.

Annual Fund Operating Expenses

(expenses that you pay each year as a percentage of the value of your investment)	Institutional Class		Retail Class		Class N
Management fees	0.75	%	0.75	%	0.75	%
Distribution and/or service (12b-1) fees	0.00	%	0.25	%	0.00	%
Other expenses	0.20	%	0.20	%	0.08	%
Total annual fund operating expenses	0.95	%	1.20	%	0.83	%
Fee waiver and/or expense reimbursement 1	0.00	%	0.00	%	0.00	%
Total annual fund operating expenses after fee waiver and/or expense reimbursement	0.95	%	1.20	%	0.83	%

1Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.00%, 1.25% and 0.95% of the Fund's average daily net assets for Institutional Class shares, Retail Class shares and Class N shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through January 31, 2018 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Adviser will be permitted to recover, on a class-by-class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below the applicable expense limitations for Institutional Class shares, Retail Class shares and Class N shares. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

Example

The example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and the Fund's operating expenses remain the same.  Although your actual costs may be higher or lower, based on these assumptions your costs would be:

	1 year		3 years		5 years		10 years
Institutional Class	$	97	$	303	$	525	$	1,166
Retail Class	$	122	$	381	$	660	$	1,455
Class N	$	85	$	265	$	460	$	1,025

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During its most recently ended fiscal year, the Fund's portfolio turnover rate was 56% of the average value of its portfolio.

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INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

The Fund normally will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in the equity securities of "small-cap companies," including preferred stocks, warrants, securities convertible into common or preferred stocks and other equity-like interests in an entity. Currently, the Fund defines a small-cap company to be one whose market capitalization either falls within the capitalization range of the Russell 2000^® Index, an index that tracks stocks of 2,000 of the smallest U.S. companies, or is $3 billion or less at the time of investment. The Fund may invest the rest of its assets in companies of any size, including large-capitalization companies.

In deciding which securities to buy and sell, Loomis Sayles typically seeks to identify companies that it believes have distinctive products, technologies, or services; dynamic earnings growth; prospects for high levels of profitability; and solid management. Loomis Sayles typically does not consider current income when making buy and sell decisions.

The Fund may invest any portion of its assets in securities of Canadian issuers and up to 20% of its assets in other foreign securities, including emerging markets securities. Although certain equity securities purchased by the Fund may be issued by domestic companies incorporated outside of the United States, the Adviser does not consider these securities to be foreign if they are included in the U.S. equity indices published by S&P Global Ratings or Russell Investments. The Fund may also invest in securities issued pursuant to Rule 144A under the Securities Act of 1933 ("Rule 144A securities").

The Fund may engage, for hedging and investment purposes, in foreign currency transactions, options and futures transactions.

Principal Risks

The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund.

Credit/Counterparty Risk is the risk that the issuer or guarantor of a fixed-income security in which the Fund invests, or the counterparty to a derivatives or other transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations.

Currency Risk is the risk that the value of the Fund's investments will fall as a result of changes in exchange rates. Loomis Sayles may elect not to hedge currency risk or may hedge imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged.

Derivatives Risk is the risk that the value of the Fund's derivative investments such as forward currency contracts, options and futures transactions will fall, for example, because of changes in the value of the underlying reference instruments, pricing difficulties or lack of correlation with the underlying investments. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. There is also the risk that the Fund may be unable to terminate or sell a derivatives position at an advantageous time or price.  The Fund's derivative counterparties may experience financial difficulties or otherwise be unwilling or unable to honor their obligations, possibly resulting in losses to the Fund.  This risk is greater for forward currency contracts and other over-the-counter traded derivatives. Investing in derivatives gives rise to other risks, such as leverage risk, liquidity risk, credit/counterparty risk, interest rate risk and market/issuer risk. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used.

Emerging Markets Risk is the risk that the Fund's investments in emerging markets may face greater foreign securities risk. Emerging markets investments are subject to greater risks arising from political or economic instability, nationalization or confiscatory taxation, currency exchange restrictions and an issuer's unwillingness or inability to make principal or interest payments on its obligations. Emerging markets companies may be smaller and have shorter operating histories than companies in developed markets.

Equity Securities Risk is the risk that the value of a stock may decline for a number of reasons that relate directly to the issuer, such as management performance, financial leverage and reduced demand for the issuer's goods and services, or the equity markets generally. Growth stocks are generally more sensitive to market movements than other types of stocks, primarily because their stock prices are based heavily on future expectations. If Loomis Sayles' assessment of the prospects for a company's growth is wrong, or if Loomis Sayles' judgment of how other investors will value the company's growth is wrong, then the price of the company's stock may fall or not approach the value that Loomis Sayles has placed on it. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer's bonds generally take precedence over the claims of those who own preferred stock or common stock.

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Foreign Securities Risk is the risk that the value of the Fund's foreign investments will fall as a result of foreign political, social, economic, environmental, credit, informational or currency changes or other issues relating to foreign investing generally. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity. The Fund's investments in foreign securities may be subject to foreign withholding or other taxes, which would decrease the yield on those securities.

Leverage Risk is the risk associated with securities or practices (e.g., borrowing and the use of certain derivatives) and investment in certain types of derivatives that multiply small index, market or asset price movements into larger changes in value. Use of derivative instruments may involve leverage. When a derivative is used as a hedge against an offsetting position that the Fund also holds, any gains generated by the derivative should be substantially offset by losses on the hedged instrument, and vice versa. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. Futures and forward currency contracts are derivatives and may be subject to this type of risk.

Liquidity Risk is the risk that the Fund may be unable to find a buyer for its investments when it seeks to sell them or to receive the price it expects. Events that may lead to increased redemptions, such as market disruptions or increases in interest rates, may also negatively impact the liquidity of the Fund's investments when it needs to dispose of them. If the Fund is forced to sell its investments at an unfavorable time and/or under adverse conditions in order to meet redemption requests, such sales could negatively affect the Fund. Securities acquired in a private placement, such as Rule 144A securities, are generally subject to significant liquidity risk because they are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Liquidity issues may also make it difficult to value the Fund's investments.

Management Risk is the risk that Loomis Sayles' investment techniques will be unsuccessful and cause the Fund to incur losses.

Market/Issuer Risk is the risk that the market value of the Fund's investments will move up and down, sometimes rapidly and unpredictably, based upon overall market and economic conditions, as well as a number of reasons that directly relate to the issuers of the Fund's investments, such as management performance, financial condition and demand for the issuers' goods and services.

Small-Capitalization Companies Risk is the risk that the Fund's investments may be subject to more abrupt price movements, limited markets, increased volatility and less liquidity than investments in larger, more established companies, which could adversely affect the value of the portfolio.

Risk/Return Bar Chart and Table

The following bar chart and table give an indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the one-year, five-year, ten-year and life-of-class periods compare to those of a broad measure of market performance. The Fund's past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at www.loomissayles.com and/or by calling the Fund toll-free at 800-633-3330.

Total Returns for Institutional Class Shares

Highest Quarterly Return:
Fourth Quarter 2010, 18.10% Lowest Quarterly Return:
Fourth Quarter 2008, -26.86%

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Average Annual Total Returns
(for the periods ended December 31, 2016)	Past 1 Year		Past 5 Years		Past 10 Years		Life of Class N (2/1/13)
Institutional Class - Return Before Taxes	5.72	%	11.97	%	8.94	%	-
Return After Taxes on Distributions	5.72	%	10.50	%	8.23	%	-
Return After Taxes on Distributions and Sale of Fund Shares	3.24	%	9.49	%	7.31	%	-
Retail Class - Return Before Taxes	5.46	%	11.66	%	8.65	%	-
Class N - Return Before Taxes	5.85	%	-		-		10.79%
Russell 2000® Growth Index	11.32	%	13.74	%	7.76	%	11.75%

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.  The after-tax returns are shown for the Institutional Class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.

MANAGEMENT

Investment Adviser

Loomis, Sayles & Company, L.P. ("Loomis Sayles")

Portfolio Managers

Mark F. Burns, CFA^®, Vice President of Loomis Sayles, has served as a portfolio manager of the Fund since 2005.

John J. Slavik, CFA^®, Vice President of Loomis Sayles, has served as a portfolio manager of the Fund since 2005.

PURCHASE AND SALE OF FUND SHARES

The following chart shows the investment minimum for each class of shares of the Fund:

	Minimum Initial Investment	Minimum Subsequent Investment
Institutional Class	$100,000	$50
Retail Class	$2,500	$50
Class N
Any account other than those listed below	$1,000,000	No Minimum
Certain Retirement Plans held in an omnibus      fashion and fund of funds that are distributed      by NGAM Distribution, L.P.	No Minimum	No Minimum

Institutional Class shares of the Fund are available to Fund trustees, former Fund trustees, employees of affiliates of the Loomis Sayles Funds and other individuals who are affiliated with any Loomis Sayles Fund (this also applies to any spouse, parents, children, siblings, grandparents, grandchildren and in-laws of those mentioned) with no initial or subsequent investment minimum. Institutional Class shares are also available with no initial or subsequent investment minimum for accounts associated with wrap-fee programs sponsored by certain broker-dealers and investment advisers and Certain Retirement Plans.

The Fund is closed to new investors; however, in its sole discretion, Loomis Sayles may permit an investor in another Loomis Sayles managed fund or product that follows the same investment strategy as the Fund to transfer assets from that fund or product into the Fund. Loomis Sayles may determine to reopen the Fund for investment at any time without notice to shareholders. For more information see the section "How to Purchase Shares" in the Statutory Prospectus.

The Fund's shares are available for purchase (and are redeemable on any business day) through your financial adviser, through your broker-dealer, directly from the Fund by writing to the Fund at Loomis Sayles Funds, P.O. Box 219594, Kansas City, MO 64121-9594, by exchange, by wire, by internet at www.loomissayles.com, by telephone at 800-633-3330, through the Automated Clearing House system, or, in the case of redemptions, by the Systematic Withdrawal Plan.

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TAX INFORMATION

Fund distributions are generally taxable to you as ordinary income or capital gains, except for distributions to retirement plans and other investors that qualify for tax-advantaged treatment under U.S. federal income tax law generally. Investments in such tax-advantaged plans will generally be taxed only upon withdrawal of monies from the tax-advantaged arrangement.

PAYMENTS TO BROKER-DEALERS AND OTHER FINANCIAL INTERMEDIARIES

If you purchase the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies may pay the intermediary for the sale of the Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your financial advisor  or visit your financial intermediary's website for more information.

M-LSUSCG77-0217

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