[Janus letterhead]

March 26, 2008

VIA EDGAR

Mr. Larry Greene
Division of Investment Management
U.S. Securities and Exchange Commission
100 F Street, N.E.
Washington, DC 20549-0505

Re: JANUS INVESTMENT FUND (the "Registrant")
    1933 Act File No. 002-34393
    1940 Act File No. 811-1879
    Post-Effective Amendment No. 121

Dear Mr. Greene:

On behalf of the Registrant and its funds or portfolios (each, a "Fund" and
collectively, the "Funds"), this letter is to respond to your comments made by
telephone on January 24, 2008 with respect to the Registrant's Post-Effective
Amendment No. 121 filed pursuant to Rule 485(a) under the Securities Act of
1933, as amended, on December 14, 2007. The Staff of the Securities and Exchange
Commission's (the "Staff") comments and the Registrant's responses to Staff
comments are as follows:

1.   COMMENT: The Staff requested that the Registrant reflect in writing all
     comments and responses and carry over comments, as applicable, to the
     Registrant's other Prospectuses and Statements of Additional Information
     ("SAIs").

     RESPONSE: The Registrant acknowledges the comment and confirms that it has
     complied.

2.   COMMENT: The Staff requested that comments provided by telephone on
     November 14, 2007 with respect to Janus Adviser Series Post-Effective
     Amendment No. 41 be carried over, as applicable, to the Funds comprising
     the Registrant's Post-Effective Amendment No. 121.

     RESPONSE: The Registrant acknowledges the comment and confirms that it has
     complied.

Janus Equity Funds - Prospectus (Retail Version)

3.   COMMENT: With respect to the Funds, the Staff noted that in the cases of
     Funds with global, international or worldwide in their names, such Funds
     should each invest in securities of at least ten countries and invest at
     least 40% of their respective assets in securities of foreign countries,
     excluding the U.S.

     RESPONSE: Consistent with investment policies and restrictions of these
     Funds, the Registrant has previously added or revised disclosure as
     appropriate to reflect that such Funds invest in several countries. The
     Registrant believes these investment policies are consistent with formal
     SEC guidance.



4.   COMMENT: With respect to Janus Fund, the Staff asked how the statement "The
     Fund may also lend portfolio securities on a short-term or long-term basis,
     up to one-third of its total assets," is consistent with the Fund's growth
     objective and strategy.

     RESPONSE: Consistent with the Fund's investment objective of seeking long
     term growth of capital in a manner consistent with the preservation of
     capital, the Fund participates in a securities lending program to generate
     additional revenue. Securities in the program are lent on a fully
     collateralized basis, which is also consistent with the Fund's goal of
     preserving capital. Securities lending is not intended to be used as a
     principal investment strategy for the Fund.

5.   COMMENT: With respect to disclosure pertaining to the nondiversification
     classification of certain Funds, the Staff stated its view that Rule 13a-1
     under the Investment Company Act of 1940, as amended (the "1940 Act"), is
     intended to apply to nondiversified funds which temporarily become
     diversified, not nondiversified funds which normally operate as diversified
     funds. It was the Staff's opinion that the disclosure should accurately
     reflect each Fund's subclassification consistent with this view.

     RESPONSE: As discussed, the disclosure indicates when a Fund is classified
     as nondiversified. Item 2 of Form N-1A indicates that a Fund classified as
     nondiversified include disclosure that it "may" invest a larger portion of
     its assets in fewer issuers. The Registrant believes its disclosure is
     consistent with Form N-1A.

6.   COMMENT: The Staff asked for clarification regarding the management of
     Janus Fundamental Equity Fund and Janus Research Fund and whether the Funds
     have a policy for investing in certain sectors.

     RESPONSE: Disclosure reflects that James Goff, Director of Research, is
     responsible for the day-to-day operations of each Fund, and the Registrant
     believes that such disclosure is consistent with Item 5 of Form N-1A.
     Neither Fund has a policy to invest in certain sectors but each has the
     flexibility to invest broadly in any sector.

7.   COMMENT: With respect to Janus Growth and Income Fund's strategy to
     normally invest up to 75% of its assets in equity securities, the Staff
     asked whether or not investments in derivatives could account for the
     entire 75%, and if so, requested that the Registrant make that point clear
     to investors.

     RESPONSE: To the extent that a derivative has equity exposure, that
     derivative may be counted as part of the 75% and if the Fund invests 75% of
     its assets in these types of derivatives, the 75% investment in equity
     securities could be comprised of all derivatives. To the extent that the
     Fund's exposure to derivatives comprises a significant portion of the 75%
     investment in equity securities, the Registrant would consider what
     additional disclosure is appropriate.

8.   COMMENT: With respect to Janus Growth and Income Fund and the strategy
     statement "Eligible equity securities...include other securities with
     equity characteristics (including the use of swaps)," the Staff indicated
     the Registrant should ensure that appropriate risk disclosure is reflected.

     RESPONSE: The Registrant acknowledges the comment and believes that
     appropriate risk disclosure has been included.

9.   COMMENT: With respect to Janus Global Opportunities Fund, the Staff asked
     if the Fund had a large, single country emerging markets investment and, if
     so, indicated that the percentage of any country concentration should be
     disclosed in the Prospectus.



     RESPONSE: In response to prior Staff comment regarding emerging markets
     disclosure, the Registrant has included the specific percentage of emerging
     markets allocation as of a Fund's fiscal year end, as applicable. The
     Registrant believes that specific country allocation is more appropriate in
     shareholder reports and Form N-Q. As previously discussed with and agreed
     to by the Staff, disclosure was previously added directing investors to
     shareholder reports and Form N-Q for a summary of investments by country in
     order that investors may have the most up-to-date information.

10.  COMMENT: With respect to disclosure regarding Anti-Money Laundering Program
     requirements under the USA PATRIOT Act, the Staff indicated that the
     disclosure did not state that the Registrant had designated an officer of
     the Funds for purposes of supervising the Registrant's anti-money
     laundering program.

     RESPONSE: As discussed during the call, the Trustees of the Registrant have
     designated an officer to supervise the anti-money laundering program, and
     the Registrant has noted the designated officer in the Trustees and
     Officers table of the SAI.

11.  COMMENT: The Staff indicated that certain other disclosure contained in the
     Prospectus appeared in all capital letters and requested a different form
     of presentation.

     RESPONSE: As discussed during the call, the disclosure referenced appears
     in bold face type within the Prospectus, not all capital letters. The EDGAR
     process converts bold face type into all capital letters.

12.  COMMENT: The Staff referenced the Funds' ability to invest in inverse
     floaters and recommended that appropriate risk disclosure be made relating
     to this type of investment.

     RESPONSE: As discussed during the call, the reference noted is in the
     "Glossary of Investment Terms." Further, the Registrant believes that
     appropriate risk disclosure is reflected in the Funds' SAI.

Janus Smart Portfolios - Prospectus (Retail Version)

13.  COMMENT: The Staff indicated that it may request, in future reviews,
     additional disclosure regarding expense recoupment by Janus Capital
     permitted pursuant to expense limitation agreements between the Registrant
     and Janus Capital.

     RESPONSE: The Registrant confirms that Janus Capital has the ability to
     recoup certain expenses as described in a Fund's expense limitation
     agreement. As previously discussed, the contractual expense waivers apply
     if total operating expenses (excluding certain expenses) exceed a certain
     limit, and recoupment is only possible if the expense ratio falls below the
     expense limit, and only for a period of three years subsequent to the
     Fund's commencement of operations.

14.  COMMENT: The Staff indicated that there appears to be a conflict between
     disclosure in the SAI which states the Funds have no industry
     concentration, and disclosure in the Prospectus which indicates that
     indirect concentration may occur.

     RESPONSE: While the Funds do not have a 1940 Act concentration policy,
     their investments among underlying funds may result in 'indirect'
     concentration. Such disclosure is intended as a risk factor and not
     specific industry concentration.



Janus Bond and Money Market Funds - Prospectus (Institutional Version)

15.  COMMENT: With respect to Janus Short-Term Bond Fund, the Staff asked how
     the policy of investing in intermediate-term fixed-income securities is
     consistent with the Fund's name.

     RESPONSE: The adopting release for Rule 35d-1 (the Fund Names Rule) and its
     accompanying "Frequently Asked Questions" notes that funds with
     "short-term" in their names should maintain a dollar-weighted average
     maturity of no more than three years but that a fund is not required to
     invest 80% of its assets in "short-term" bonds. Although this Fund may
     invest in intermediate-term fixed-income securities, the Fund's policy
     disclosed in the Prospectus is to maintain an average-weighted effective
     maturity of three years or less under normal circumstances.

16.  COMMENT: With respect to Janus Tax-Exempt Money Market Fund, the Staff
     asked why the Registrant felt it was appropriate to reflect the Fund's
     performance with the effect of expense waivers.

     RESPONSE: Form N-1A, as well as previous SEC interpretative letters,
     indicates total returns are calculated using the methodology utilized in
     the Fund's financial highlights. For purposes of the Fund's financial
     highlights, total return is calculated using an expense ratio that is
     inclusive of any expense waivers. Accordingly, the Registrant reflects
     performance with the effect of expense waivers in the Prospectus.

17.  COMMENT: With respect to the fee table and the footnote referencing
     contractual expense waiver information, the Staff recommended that the
     Registrant amend the footnote to include the specific expense waiver limit
     rather than referring to the SAI.

     RESPONSE: As discussed during the call, the expense waiver for the Funds
     does not "cap" total expenses but instead places a limit on certain
     expenses and excludes other expenses from the waiver, as described in the
     footnote to the fee table. The Registrant believes that including the
     expense waiver limit may be confusing to shareholders who may read it as a
     cap on total expenses. The Registrant believes that the current
     presentation, along with associated disclosure in the SAI, provides
     shareholders with enough information to understand the application of the
     expense limitations without risking investor confusion. The Registrant
     intends, however, to consider enhancing its disclosure for future
     amendments.

Janus Venture Fund - Prospectus (Retail Version)

18.  COMMENT: With respect to a question pertaining to the risks associated with
     short sales, the Staff asked whether or not there was a strategy discussion
     related to the Fund's use of short sales.

     RESPONSE: Consistent with the investment strategies and risks of the Fund,
     the Registrant deleted the referenced question and added a general risk
     discussion under the "General Portfolio Policies" section.

19.  COMMENT: The Staff indicated that language regarding maintaining liquidity
     contained in the "Cash Position" section should be revised.

     RESPONSE: The Registrant believes the disclosure describing the Fund's
     ability to temporarily increase its cash position, under unusual
     circumstances, to protect assets or maintain liquidity in certain
     circumstances (e.g., to meet unusually large redemptions) is appropriate
     and no modifications are necessary at this time.



Janus Mid Cap Value Fund - Institutional Shares Prospectus (Institutional
Version)

20.  COMMENT: With respect to general disclosure pertaining to foreign
     securities, the Staff asked whether or not Janus Mid Cap Value Fund had
     investments in emerging market countries, and if so, asked that appropriate
     disclosure be added.

     RESPONSE: As discussed during the call, the Fund does not generally invest
     in foreign securities, although it is not precluded from doing so. If this
     changes, the Registrant would consider what additional disclosure regarding
     investments in foreign securities in general, as well as emerging markets,
     is appropriate.

21.  COMMENT: With respect to disclosure regarding Anti-Money Laundering Program
     requirements under the USA PATRIOT Act, the Staff asked for clarification
     related to the statement "your financial intermediary is required..."
     asking specifically if the Registrant knows whether or not the financial
     intermediary has appointed an Anti-Money Laundering officer.

     RESPONSE: As discussed during the call, each service provider represents by
     agreement that it is in compliance with all applicable anti-money
     laundering laws, rules and regulations including, but not limited to, the
     USA PATRIOT Act of 2001, P.L. 107-56 and that it has policies and
     procedures in place to detect money laundering and terrorist financing,
     including the reporting of suspicious activity.

Janus Money Market Funds - Investor Shares Statement of Additional Information

22.  COMMENT: With respect to risk disclosure related to investments in
     mortgage-backed securities comprised of subprime mortgages, the Staff asked
     whether or not this risk applied to Funds other than Janus Money Market
     Fund.

     RESPONSE: The Registrant continues to review whether this risk disclosure
     is appropriate for inclusion in other Funds' respective Prospectus and SAI
     disclosures.

Janus Equity and Bond Funds - Statement of Additional Information

23.  COMMENT: With respect to disclosure related to venture capital investments,
     the Staff asked if there is appropriate related risk disclosure.

     RESPONSE: The Registrant acknowledges the comment and believes that
     appropriate risk disclosure is included in the SAI.

24.  COMMENT: With respect to disclosure relating to short sales, specifically
     the statement "...the Fund may designate liquid assets it owns (other than
     the short sales proceeds) as segregated assets to the books of the broker
     and/or its custodian in an amount equal to its obligation..." the Staff
     asked if the process of segregating assets to a broker are consistent with
     SEC rules.

     RESPONSE: The Registrant acknowledges the comment and believes that the
     process is consistent with SEC guidance.

25.  COMMENT: With respect to general disclosure under "Investment Company
     Securities" related to investments in exchange-traded funds, the Staff
     indicated that the Registrant should include disclosure stating that
     certain related expenses may be duplicative.



     RESPONSE: The Registrant acknowledges the comment and believes that
     appropriate risk disclosure is included.

26.  COMMENT: With respect to disclosure related to options on foreign
     currencies, forward contracts, and foreign instruments, the Staff asked
     about underlying instruments to the derivatives.

     RESPONSE: The Registrant acknowledges the comment and believes the SAI
     includes discussion regarding each type of derivative.

27.  COMMENT: To the extent that the Registrant utilizes American style options
     and European style options, the Staff indicated that the Registrant should
     include disclosure discussing the differences between each style of option
     investing.

     RESPONSE: The Registrant acknowledges the comment and believes that the
     current disclosure is appropriate based on current investment practices.

28.  COMMENT: The Staff requested that the Registrant provide a Tandy
     representation in a response letter to be filed as correspondence separate
     from the filing.

     RESPONSE: The Registrant provides its response below.

The Registrant acknowledges responsibility for the adequacy and accuracy of the
disclosure in the filings. In addition, the Registrant acknowledges that Staff
comments, or changes to disclosure in response to Staff comments in the filings
reviewed by the Staff, do not foreclose the Commission from taking any action
with respect to the filing.

If you have any concerns regarding the above responses, please call me at (303)
336-4045. Thank you for your assistance in this matter.

Regards,


/s/ Robin Nesbitt

Robin Nesbitt
Associate Counsel

cc: Stephanie Grauerholz-Lofton, Esq.
    Cindy Antonson
    Donna Brungardt