485BPOS

Registration Nos. 2-98326

811-04323

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

FORM N-1A

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933	¨
Pre-Effective Amendment No.	¨
Post-Effective Amendment No. 106	x

and/or

REGISTRATION STATEMENT

UNDER

THE INVESTMENT COMPANY ACT OF 1940	¨
Amendment No. 107	x
(Check appropriate box or boxes.)

NATIXIS FUNDS TRUST I

(Exact Name of Registrant as Specified in Charter)

399 Boylston Street, Boston, Massachusetts 02116

(Address of principal executive offices) (Zip Code)

Registrant’s Telephone Number, including Area Code (617) 449-2810

Coleen Downs Dinneen, Esq.

NGAM Distribution, L.P.

399 Boylston Street

Boston, Massachusetts 02116

(Name and Address of Agent for Service)

Copy to:

John M. Loder, Esq.

Ropes & Gray

800 Boylston Street

Boston, Massachusetts 02110

Approximate Date of Proposed Public Offering

It is proposed that this filing will become effective (check appropriate box):

x immediately upon filing pursuant to paragraph (b)

¨ on          pursuant to paragraph (b)

¨ 60 days after filing pursuant to paragraph (a)(1)

¨ on (date) pursuant to paragraph (a)(1)

¨ 75 days after filing pursuant to paragraph (a)(2)

¨ on (date) pursuant to paragraph (a)(2) of Rule 485.

If appropriate, check the following box:

¨ This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

NATIXIS FUNDS TRUST I

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all of the requirements for effectiveness of this registration statement under Rule 485(b) under the Securities Act and has duly caused this Post-Effective Amendment No. 106 to its Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of Boston, and the Commonwealth of Massachusetts on the 21^st day of February, 2014.

NATIXIS FUNDS TRUST I
By:	/s/ David L. Giunta
	David L. Giunta
	President and Chief Executive Officer

Pursuant to the requirements of the Securities Act of 1933, as amended, this amendment to the Registration Statement has been signed below by the following persons in the capacities and on the date indicated.

Signature	Title	Date
/s/ David L. Giunta David L. Giunta	President, Chief Executive Officer and Trustee	February 21, 2014
/s/ Michael C. Kardok Michael C. Kardok	Treasurer	February 21, 2014
Robert J. Blanding* Robert J. Blanding	Trustee	February 21, 2014
Daniel M. Cain* Daniel M. Cain	Trustee	February 21, 2014
Kenneth A. Drucker* Kenneth A. Drucker	Trustee	February 21, 2014
Edmond J. English* Edmond J. English	Trustee	February 21, 2014
John T. Hailer* John T. Hailer	Trustee	February 21, 2014
Wendell J. Knox * Wendell J. Knox	Trustee	February 21, 2014
Martin T. Meehan* Martin T. Meehan	Trustee	February 21, 2014
Sandra O. Moose* Sandra O. Moose	Trustee, Chairperson of the Board	February 21, 2014
Erik R. Sirri * Erik R. Sirri	Trustee	February 21, 2014
Peter J. Smail * Peter J. Smail	Trustee	February 21, 2014
Cynthia L. Walker* Cynthia L. Walker	Trustee	February 21, 2014

*By:	/s/ Russell Kane
Russell Kane
Attorney-In-Fact1
February 21, 2014

¹  Powers of Attorney for Robert J. Blanding, Daniel M. Cain, John T. Hailer and Sandra O. Moose are incorporated by reference to exhibit (q) to PEA No. 58 to the Registration Statement filed on December 2, 2004. Power of Attorney for Cynthia L. Walker is incorporated by reference to exhibit (q)(2) to PEA No. 62 to the Registration Statement filed on August 18, 2005. Power of Attorney for Kenneth A. Drucker is incorporated by reference to exhibit (q)(4) to PEA No. 74 to the Registration Statement filed on July 17, 2008. Power of Attorney for Wendell J. Knox is incorporated by reference to exhibit (q)(4) to PEA No. 79 to the Registration Statement filed on November 23, 2009. Powers of Attorney for Erik R. Sirri and Peter J. Smail are incorporated by reference to exhibits (q)(5) and (q)(6) to PEA No. 80 to the Registration Statement filed on December 11, 2009. Power of Attorney for Martin T. Meehan is incorporated by reference to exhibit (q)(8) to PEA No. 98 to the Registration Statement filed on November 29, 2012. Power of Attorney for Edmond J. English is filed incorporated by reference to exhibit (q)(10) to PEA No 101 to the Registration Statement filed on January 28, 2013.

Natixis Funds Trust I

Exhibit Index

Exhibits for Item 28 of Form N-1A

Exhibit	Exhibit Description
EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-101.CAL	XBRL Taxonomy Extension Calculation Linkbase
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Objective [Heading]

rr_ObjectiveHeading

Investment Goal

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks high total investment return through a combination of current income and capital appreciation.

Expense [Heading]

rr_ExpenseHeading

Fund Fees & Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in the Natixis Fund Complex. More information about these and other discounts is available from your financial professional and in the section "How Sales Charges Are Calculated" on page 52 of the Prospectus and on page 112 in the section "Reduced Sales Charges" of the Statement of Additional Information ("SAI").

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in the Natixis Fund Complex.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 100,000

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees

(fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses

(expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

2015-01-31

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This 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 (except where indicated). The example also assumes that your investment has a 5% return each year and that 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:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

If shares are redeemed:

Expense Example, No Redemption, By Year, Caption [Text]

rr_ExpenseExampleNoRedemptionByYearCaption

If shares are not redeemed:

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

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 107% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

107.00%

Strategy [Heading]

rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in bonds, which include debt securities of any maturity. In addition, the Fund normally will invest primarily in investment grade securities. "Investment grade" securities are those securities that are rated in one of the top four ratings categories at the time of purchase by at least one of the three major ratings agencies (Moody's Investors Service, Inc. ("Moody's"), Fitch Investors Services, Inc. ("Fitch") or Standard and Poor's Ratings Group ("S&P")), or, if unrated, are determined by the Adviser to be of comparable quality. For purposes of this restriction, investment grade securities also include cash and cash equivalent securities. The Fund will generally seek to maintain an effective duration of +/- 2 years relative to the Barclays U.S. Aggregate Bond Index. Duration is a measure of the expected life of a fixed-income security that is used to determine the sensitivity of a security's price to changes in interest rates. A fund with a longer average portfolio duration will be more sensitive to changes in interest rates than a fund with a shorter average portfolio duration. By way of example, the price of a bond fund with an average duration of five years would be expected to fall approximately 5% if interest rates rose by one percentage point. While the effective duration for the Barclays U.S. Aggregate Bond Index fluctuates, as of December 31, 2013, the effective duration was approximately 5.5 years. The Fund may also invest up to 20% of its assets, at the time of purchase, in bonds rated below investment grade (i.e., none of the three major ratings agencies (Moody's, Fitch or S&P) have rated the securities in one of their top four ratings categories) (commonly known as "junk bonds"), or, if unrated, securities determined by the Adviser to be of comparable quality, and up to 10% of its assets in non-U.S. dollar-denominated securities. There is no minimum rating for the securities in which the Fund may invest.

The Fund's investments may include securities issued by U.S. and non-U.S. corporations and governments, securities issued by supranational entities, U.S. government-sponsored agency debenture and pass-through securities and commercial mortgage-backed and other asset-backed securities.

The portfolio management team seeks to build and manage a portfolio that will perform well on a benchmark-relative and, secondarily, on an absolute basis in the market environment it anticipates over the short to intermediate term. The primary factors for broad sector positioning are the Adviser's expected performance of sectors in the benchmark and the incremental performance or diversification benefits the Fund's portfolio managers anticipate from opportunistic allocations to securities that are not included in the Fund's benchmark. In addition, the Fund's portfolio managers will look at individual security selection, position size and overall duration contribution to the portfolio.

Purchase and sale considerations also include overall portfolio yield, interest rate sensitivity across different maturities held, fixed-income sector fundamentals and outlook, technical supply/demand factors, credit risk, cash flow variability, security optionality and structure, as well as potential currency and liquidity risk. The Adviser also considers economic factors. Individual securities are assessed on a risk/return basis, both on a benchmark-relative and on an absolute return basis, and on their fit within the overall portfolio strategy.

Specifically, the Adviser follows a total return-oriented investment approach and considers broad sector allocation, quality and liquidity bias, yield curve positioning and duration in selecting securities for the Fund. The Fund's portfolio managers consider economic and market conditions as well as issuer-specific data, such as fixed-charge coverage, the relationship between cash flows and debt service obligations, the experience and perceived strength of management or security structure, price responsiveness of the security to interest rate changes, earnings prospects, debt as a percentage of assets, borrowing requirements, debt maturity schedules and liquidation value.

In selecting investments for the Fund, the Adviser's research analysts and sector teams work closely with the Fund's portfolio managers to develop an outlook for the economy from research produced by various financial firms and specific forecasting services or from economic data released by U.S. and foreign governments, as well as the Federal Reserve Bank. The analysts conduct a thorough review of individual securities to identify what they consider attractive values in the high quality bond market through the use of quantitative tools such as internal and external computer systems and software. The Adviser continuously monitors an issuer's creditworthiness or cash flow stability to assess whether the obligation remains an appropriate investment for the Fund. It may relax its emphasis on quality with respect to a given security if it believes that the issuer's financial outlook is promising. This may create an opportunity for higher returns. The Adviser seeks to balance opportunities for yield and price performance by combining macro economic analysis with individual security selection. Fund holdings are generally diversified across sectors and industry groups such as utilities or telecommunications, which tend to move independently of the ebbs and flows in economic growth.

In connection with its principal investment strategies, the Fund may also invest in securities issued pursuant to Rule 144 under the Securities Act of 1933 ("Rule 144A securities"), structured notes, foreign securities, including those in emerging markets, mortgage-related securities, including mortgage dollar rolls, futures and swaps (including credit default swaps). The Fund may use such derivatives for hedging or investment purposes. The Fund may also engage in currency transactions. The Adviser may elect not to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

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.

Below Investment Grade Fixed-Income Securities Risk: The Fund's investments in below investment grade fixed-income securities, also known as "junk bonds," may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit risk (including a greater risk of default) and liquidity risk. The ability of the issuer to make principal and interest payments is predominantly speculative for below investment grade fixed-income securities.

Credit Risk: Credit risk is the risk that the issuer or the guarantor of a fixed-income security, 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: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest) can be used to acquire or to transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund's exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund's liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those that would have occurred had derivatives not been used. The Fund's use of derivatives, such as forward currency contracts, structured notes, futures transactions and swap transactions involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward currency contracts, swaps and other over-the-counter traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than the initial margin required to initiate derivatives positions. 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.

Emerging Markets Risk: In addition to the risks of investing in foreign investments generally, 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.

Fixed-Income Securities Risk: Fixed-income securities are subject to credit risk, interest rate risk and liquidity risk. You may lose money on your investment due to unpredictable drops in a security's value or periods of below-average performance in a given security or in the securities market as a whole. Rule 144A securities and structured notes may be more illiquid than other fixed income securities. In addition, an economic downturn or period of rising interest rates could adversely affect the market of these securities and reduce the Fund's ability to sell them.

Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit and information risks. The Fund's investments in foreign securities also are subject to foreign currency fluctuations and other foreign currency-related risks. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity.

Interest Rate Risk: Is the risk that the value of the Fund's investments will fall if interest rates rise. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. Interest rate risk generally is greater for funds that invest in fixed-income securities with relatively longer durations than for funds that invest in fixed-income securities with shorter durations. In addition, an economic downturn or period of rising interest rates could adversely affect the market of these securities and reduce the Fund's ability to sell them. A period of rising interest rates could negatively impact the performance of the Fund.

Issuer Risk: The value of the Fund's investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer's goods and services.

Leverage Risk: Use of derivative instruments may involve leverage. Leverage is the risk associated with securities or practices that multiply small index, market or asset-price movements into larger changes in value. The use of leverage increases the impact of gains and losses on a fund's returns, and may lead to significant losses if investments are not successful.

Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from transacting in these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value.

Management Risk: A strategy used by the Fund's portfolio managers may fail to produce the intended result.

Market Risk: The market value of a security or portfolio will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer's financial condition, as well as overall market and economic conditions.

Mortgage-Related and Asset-Backed Securities Risk: In addition to the risks associated with investments in fixed-income securities generally (for example, credit, liquidity and valuation risk), mortgage-related and asset-backed securities are subject to the risks of the mortgages and assets underlying the securities as well as prepayment risk, the risk that the securities may be prepaid and result in the reinvestment of the prepaid amounts in securities with lower yields than the prepaid obligations. Conversely, there is a risk that an unexpected rise in interest rates will extend the life of a mortgage-related or asset-backed security beyond the expected prepayment time, typically reducing the security's value. The Fund also may incur a loss when there is a prepayment of securities that were purchased at a premium. The Fund's investments in other asset-backed securities are subject to risks similar to those associated with mortgage-related securities, as well as additional risks associated with the nature of the assets and the servicing of those assets.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose money by investing in the Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Risk/Return Bar Chart and Table

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table shown below provide some 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, and ten-year 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 ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund's shares. A sales charge will reduce your return.

Bar Chart [Heading]

rr_BarChartHeading

Total Returns for Class A Shares

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Highest Quarterly Return: Second Quarter 2009, 7.84%
Lowest Quarterly Return: Third Quarter 2008, -4.26%

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns (for the periods ended December 31, 2013)

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

Class B total returns in the table below do not reflect the automatic conversion of Class B shares to Class A shares after eight years.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Because Class N shares did not have one calendar year of performance as of December 31, 2013, performance shown for Class N shares is that of Class Y shares of the Fund. Class N shares would have substantially similar returns because they would have been invested in the same portfolio of securities as Class Y shares and would only differ to the extent the classes did not have the same expenses. The Class N returns may be higher or lower than the returns of Class Y shares.

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-deferred 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 only one class of the Fund. The Return After Taxes on Distributions and Sale of Fund Shares for the 1-year period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses, or taxes.

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund's shares. A sales charge will reduce your return.

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund's past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

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.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

The after-tax returns are shown for only one class of the Fund.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart and table shown below provide some 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, and ten-year periods compare to those of a broad measure of market performance.

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

Index performance reflects no deduction for fees, expenses, or taxes.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

ngam.natixis.com

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

800-225-5478

Barclays U.S. Aggregate Bond Index

Risk/Return:

rr_RiskReturnAbstract

Past 1 Year

rr_AverageAnnualReturnYear01

(2.02%)

Past 5 Years

rr_AverageAnnualReturnYear05

4.44%

Past 10 Years

rr_AverageAnnualReturnYear10

4.55%

Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

4.50%

Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)

rr_MaximumDeferredSalesChargeOverOther

none

Management fees

rr_ManagementFeesOverAssets

0.38%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.16%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.79%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[1]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.79%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

527

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

691

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

869

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

1,384

Annual Return 2004

rr_AnnualReturn2004

5.10%

Annual Return 2005

rr_AnnualReturn2005

1.10%

Annual Return 2006

rr_AnnualReturn2006

5.34%

Annual Return 2007

rr_AnnualReturn2007

6.06%

Annual Return 2008

rr_AnnualReturn2008

0.61%

Annual Return 2009

rr_AnnualReturn2009

16.62%

Annual Return 2010

rr_AnnualReturn2010

10.35%

Annual Return 2011

rr_AnnualReturn2011

7.68%

Annual Return 2012

rr_AnnualReturn2012

11.31%

Annual Return 2013

rr_AnnualReturn2013

(0.82%)

Past 1 Year

rr_AverageAnnualReturnYear01

(5.28%)

Past 5 Years

rr_AverageAnnualReturnYear05

7.87%

Past 10 Years

rr_AverageAnnualReturnYear10

5.72%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarterly Return:

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

7.84%

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarterly Return:

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(4.26%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2008

Class A | Return After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Past 1 Year

rr_AverageAnnualReturnYear01

(6.89%)

Past 5 Years

rr_AverageAnnualReturnYear05

5.96%

Past 10 Years

rr_AverageAnnualReturnYear10

3.84%

Class A | Return After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Past 1 Year

rr_AverageAnnualReturnYear01

(2.98%)

Past 5 Years

rr_AverageAnnualReturnYear05

5.44%

Past 10 Years

rr_AverageAnnualReturnYear10

3.72%

Class B

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)

rr_MaximumDeferredSalesChargeOverOther

5.00%

Management fees

rr_ManagementFeesOverAssets

0.38%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.16%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.54%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[1]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.54%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

657

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

786

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,039

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

1,632

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

157

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

486

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

839

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

1,632

Past 1 Year

rr_AverageAnnualReturnYear01

(6.28%)

Past 5 Years

rr_AverageAnnualReturnYear05

7.78%

Past 10 Years

rr_AverageAnnualReturnYear10

5.44%

Class C

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)

rr_MaximumDeferredSalesChargeOverOther

1.00%

Management fees

rr_ManagementFeesOverAssets

0.38%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.16%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.54%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[1]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.54%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

257

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

486

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

839

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

1,834

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

157

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

486

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

839

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

1,834

Past 1 Year

rr_AverageAnnualReturnYear01

(2.52%)

Past 5 Years

rr_AverageAnnualReturnYear05

8.09%

Past 10 Years

rr_AverageAnnualReturnYear10

5.42%

Class N

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)

rr_MaximumDeferredSalesChargeOverOther

none

Management fees

rr_ManagementFeesOverAssets

0.38%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.06%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.44%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[1]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.44%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

45

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

141

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

246

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

555

Past 1 Year

rr_AverageAnnualReturnYear01

(0.56%)

Past 5 Years

rr_AverageAnnualReturnYear05

9.17%

Past 10 Years

rr_AverageAnnualReturnYear10

6.49%

Class Y

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)

rr_MaximumDeferredSalesChargeOverOther

none

Management fees

rr_ManagementFeesOverAssets

0.38%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.16%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.54%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[1]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.54%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

55

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

173

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

302

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 677

Past 1 Year

rr_AverageAnnualReturnYear01

(0.56%)

Past 5 Years

rr_AverageAnnualReturnYear05

9.17%

Past 10 Years

rr_AverageAnnualReturnYear10

6.49%

[1] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") and NGAM Advisors, L.P. ("NGAM Advisors"), the Fund's advisory administrator, have given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 0.80%, 1.55%, 1.55%, 0.50% and 0.55% of the Fund's average daily net assets for Class A, B, C, N and Y 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, 2015 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 0.80%, 1.55%, 1.55%, 0.50% and 0.55% of the Fund's average daily net assets for Class A, B, C, N and Y shares, respectively. 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.

XML

(Loomis Sayles Core Plus Bond Fund)

Investment Goal

The Fund seeks high total investment return through a combination of current income and capital appreciation.

Fund Fees & Expenses

The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in the Natixis Fund Complex. More information about these and other discounts is available from your financial professional and in the section "How Sales Charges Are Calculated" on page 52 of the Prospectus and on page 112 in the section "Reduced Sales Charges" of the Statement of Additional Information ("SAI").

Shareholder Fees

(fees paid directly from your investment)

Shareholder Fees (Loomis Sayles Core Plus Bond Fund) (USD $)	Class A	Class B	Class C	Class N	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	4.50%	none	none	none	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	5.00%	1.00%	none	none
Redemption fees	none	none	none	none	none

Annual Fund Operating Expenses

(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses (Loomis Sayles Core Plus Bond Fund)		Class A	Class B	Class C	Class N	Class Y
Management fees		0.38%	0.38%	0.38%	0.38%	0.38%
Distribution and/or service (12b-1) fees		0.25%	1.00%	1.00%	none	none
Other expenses		0.16%	0.16%	0.16%	0.06%	0.16%
Total annual fund operating expenses		0.79%	1.54%	1.54%	0.44%	0.54%
Fee waiver and/or expense reimbursement	[1]	none	none	none	none	none
Total annual fund operating expenses after fee waiver and/or expense reimbursement		0.79%	1.54%	1.54%	0.44%	0.54%

Example

This 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 (except where indicated). The example also assumes that your investment has a 5% return each year and that 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:

If shares are redeemed:

Expense Example (Loomis Sayles Core Plus Bond Fund) (USD $)	1 Year	3 Years	5 Years	10 Years
Class A	527	691	869	1,384
Class B	657	786	1,039	1,632
Class C	257	486	839	1,834
Class N	45	141	246	555
Class Y	55	173	302	677

If shares are not redeemed:

Expense Example, No Redemption (Loomis Sayles Core Plus Bond Fund) (USD $)	1 Year	3 Years	5 Years	10 Years
Class B	157	486	839	1,632
Class C	157	486	839	1,834

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 107% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

Under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in bonds, which include debt securities of any maturity. In addition, the Fund normally will invest primarily in investment grade securities. "Investment grade" securities are those securities that are rated in one of the top four ratings categories at the time of purchase by at least one of the three major ratings agencies (Moody's Investors Service, Inc. ("Moody's"), Fitch Investors Services, Inc. ("Fitch") or Standard and Poor's Ratings Group ("S&P")), or, if unrated, are determined by the Adviser to be of comparable quality. For purposes of this restriction, investment grade securities also include cash and cash equivalent securities. The Fund will generally seek to maintain an effective duration of +/- 2 years relative to the Barclays U.S. Aggregate Bond Index. Duration is a measure of the expected life of a fixed-income security that is used to determine the sensitivity of a security's price to changes in interest rates. A fund with a longer average portfolio duration will be more sensitive to changes in interest rates than a fund with a shorter average portfolio duration. By way of example, the price of a bond fund with an average duration of five years would be expected to fall approximately 5% if interest rates rose by one percentage point. While the effective duration for the Barclays U.S. Aggregate Bond Index fluctuates, as of December 31, 2013, the effective duration was approximately 5.5 years. The Fund may also invest up to 20% of its assets, at the time of purchase, in bonds rated below investment grade (i.e., none of the three major ratings agencies (Moody's, Fitch or S&P) have rated the securities in one of their top four ratings categories) (commonly known as "junk bonds"), or, if unrated, securities determined by the Adviser to be of comparable quality, and up to 10% of its assets in non-U.S. dollar-denominated securities. There is no minimum rating for the securities in which the Fund may invest.

The Fund's investments may include securities issued by U.S. and non-U.S. corporations and governments, securities issued by supranational entities, U.S. government-sponsored agency debenture and pass-through securities and commercial mortgage-backed and other asset-backed securities.

The portfolio management team seeks to build and manage a portfolio that will perform well on a benchmark-relative and, secondarily, on an absolute basis in the market environment it anticipates over the short to intermediate term. The primary factors for broad sector positioning are the Adviser's expected performance of sectors in the benchmark and the incremental performance or diversification benefits the Fund's portfolio managers anticipate from opportunistic allocations to securities that are not included in the Fund's benchmark. In addition, the Fund's portfolio managers will look at individual security selection, position size and overall duration contribution to the portfolio.

Purchase and sale considerations also include overall portfolio yield, interest rate sensitivity across different maturities held, fixed-income sector fundamentals and outlook, technical supply/demand factors, credit risk, cash flow variability, security optionality and structure, as well as potential currency and liquidity risk. The Adviser also considers economic factors. Individual securities are assessed on a risk/return basis, both on a benchmark-relative and on an absolute return basis, and on their fit within the overall portfolio strategy.

Specifically, the Adviser follows a total return-oriented investment approach and considers broad sector allocation, quality and liquidity bias, yield curve positioning and duration in selecting securities for the Fund. The Fund's portfolio managers consider economic and market conditions as well as issuer-specific data, such as fixed-charge coverage, the relationship between cash flows and debt service obligations, the experience and perceived strength of management or security structure, price responsiveness of the security to interest rate changes, earnings prospects, debt as a percentage of assets, borrowing requirements, debt maturity schedules and liquidation value.

In selecting investments for the Fund, the Adviser's research analysts and sector teams work closely with the Fund's portfolio managers to develop an outlook for the economy from research produced by various financial firms and specific forecasting services or from economic data released by U.S. and foreign governments, as well as the Federal Reserve Bank. The analysts conduct a thorough review of individual securities to identify what they consider attractive values in the high quality bond market through the use of quantitative tools such as internal and external computer systems and software. The Adviser continuously monitors an issuer's creditworthiness or cash flow stability to assess whether the obligation remains an appropriate investment for the Fund. It may relax its emphasis on quality with respect to a given security if it believes that the issuer's financial outlook is promising. This may create an opportunity for higher returns. The Adviser seeks to balance opportunities for yield and price performance by combining macro economic analysis with individual security selection. Fund holdings are generally diversified across sectors and industry groups such as utilities or telecommunications, which tend to move independently of the ebbs and flows in economic growth.

In connection with its principal investment strategies, the Fund may also invest in securities issued pursuant to Rule 144 under the Securities Act of 1933 ("Rule 144A securities"), structured notes, foreign securities, including those in emerging markets, mortgage-related securities, including mortgage dollar rolls, futures and swaps (including credit default swaps). The Fund may use such derivatives for hedging or investment purposes. The Fund may also engage in currency transactions. The Adviser may elect not to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

Principal Investment 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.

Below Investment Grade Fixed-Income Securities Risk: The Fund's investments in below investment grade fixed-income securities, also known as "junk bonds," may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit risk (including a greater risk of default) and liquidity risk. The ability of the issuer to make principal and interest payments is predominantly speculative for below investment grade fixed-income securities.

Credit Risk: Credit risk is the risk that the issuer or the guarantor of a fixed-income security, 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: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest) can be used to acquire or to transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund's exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund's liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those that would have occurred had derivatives not been used. The Fund's use of derivatives, such as forward currency contracts, structured notes, futures transactions and swap transactions involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward currency contracts, swaps and other over-the-counter traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than the initial margin required to initiate derivatives positions. 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.

Emerging Markets Risk: In addition to the risks of investing in foreign investments generally, 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.

Fixed-Income Securities Risk: Fixed-income securities are subject to credit risk, interest rate risk and liquidity risk. You may lose money on your investment due to unpredictable drops in a security's value or periods of below-average performance in a given security or in the securities market as a whole. Rule 144A securities and structured notes may be more illiquid than other fixed income securities. In addition, an economic downturn or period of rising interest rates could adversely affect the market of these securities and reduce the Fund's ability to sell them.

Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit and information risks. The Fund's investments in foreign securities also are subject to foreign currency fluctuations and other foreign currency-related risks. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity.

Interest Rate Risk: Is the risk that the value of the Fund's investments will fall if interest rates rise. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. Interest rate risk generally is greater for funds that invest in fixed-income securities with relatively longer durations than for funds that invest in fixed-income securities with shorter durations. In addition, an economic downturn or period of rising interest rates could adversely affect the market of these securities and reduce the Fund's ability to sell them. A period of rising interest rates could negatively impact the performance of the Fund.

Issuer Risk: The value of the Fund's investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer's goods and services.

Leverage Risk: Use of derivative instruments may involve leverage. Leverage is the risk associated with securities or practices that multiply small index, market or asset-price movements into larger changes in value. The use of leverage increases the impact of gains and losses on a fund's returns, and may lead to significant losses if investments are not successful.

Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from transacting in these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value.

Management Risk: A strategy used by the Fund's portfolio managers may fail to produce the intended result.

Market Risk: The market value of a security or portfolio will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer's financial condition, as well as overall market and economic conditions.

Mortgage-Related and Asset-Backed Securities Risk: In addition to the risks associated with investments in fixed-income securities generally (for example, credit, liquidity and valuation risk), mortgage-related and asset-backed securities are subject to the risks of the mortgages and assets underlying the securities as well as prepayment risk, the risk that the securities may be prepaid and result in the reinvestment of the prepaid amounts in securities with lower yields than the prepaid obligations. Conversely, there is a risk that an unexpected rise in interest rates will extend the life of a mortgage-related or asset-backed security beyond the expected prepayment time, typically reducing the security's value. The Fund also may incur a loss when there is a prepayment of securities that were purchased at a premium. The Fund's investments in other asset-backed securities are subject to risks similar to those associated with mortgage-related securities, as well as additional risks associated with the nature of the assets and the servicing of those assets.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some 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, and ten-year 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 ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund's shares. A sales charge will reduce your return.

Total Returns for Class A Shares

Highest Quarterly Return: Second Quarter 2009, 7.84%

Lowest Quarterly Return: Third Quarter 2008, -4.26%

Class B total returns in the table below do not reflect the automatic conversion of Class B shares to Class A shares after eight years.

Average Annual Total Returns (for the periods ended December 31, 2013)

Average Annual Total Returns (Loomis Sayles Core Plus Bond Fund)	Past 1 Year	Past 5 Years	Past 10 Years
Class A	(5.28%)	7.87%	5.72%
Class A Return After Taxes on Distributions	(6.89%)	5.96%	3.84%
Class A Return After Taxes on Distributions and Sale of Fund Shares	(2.98%)	5.44%	3.72%
Class B	(6.28%)	7.78%	5.44%
Class C	(2.52%)	8.09%	5.42%
Class N	(0.56%)	9.17%	6.49%
Class Y	(0.56%)	9.17%	6.49%
Barclays U.S. Aggregate Bond Index	(2.02%)	4.44%	4.55%

Because Class N shares did not have one calendar year of performance as of December 31, 2013, performance shown for Class N shares is that of Class Y shares of the Fund. Class N shares would have substantially similar returns because they would have been invested in the same portfolio of securities as Class Y shares and would only differ to the extent the classes did not have the same expenses. The Class N returns may be higher or lower than the returns of Class Y shares.

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-deferred 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 only one class of the Fund. The Return After Taxes on Distributions and Sale of Fund Shares for the 1-year period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses, or taxes.

[1] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") and NGAM Advisors, L.P. ("NGAM Advisors"), the Fund's advisory administrator, have given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 0.80%, 1.55%, 1.55%, 0.50% and 0.55% of the Fund's average daily net assets for Class A, B, C, N and Y 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, 2015 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 0.80%, 1.55%, 1.55%, 0.50% and 0.55% of the Fund's average daily net assets for Class A, B, C, N and Y shares, respectively. 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.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Sep. 30, 2013
Registrant Name	dei_EntityRegistrantName	Natixis Funds Trust I
Central Index Key	dei_EntityCentralIndexKey	0000770540
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Jan. 27, 2014
Document Effective Date	dei_DocumentEffectiveDate	Feb. 01, 2014
Prospectus Date	rr_ProspectusDate	Feb. 01, 2014