Exhibit 1(a)

                              JANUS INVESTMENT FUND

                            CERTIFICATE OF AMENDMENT
                            ------------------------


         The undersigned, being the Secretary of Janus Investment Fund, a trust
with transferable shares of the type commonly called a Massachusetts business
trust (the "Trust"), DOES HEREBY CERTIFY that, pursuant to the authority
conferred upon the Trustees of the Trust by Section 7.3 of the Amended and
Restated Agreement and Declaration of Trust, dated March 18, 2003, as may be
amended from time to time (the "Declaration of Trust"), and by the affirmative
vote of a majority of the Trustees at a meeting duly called and held on
September 21, 2004, the Declaration of Trust is amended as follows:

         The first paragraph of Section 4.2 of the Declaration of Trust is
hereby amended and restated in its entirety to read as follows:

         Section 4.2 Establishment and Designation of Series. Without limiting
         the authority of the Trustees set forth in Section 4.1 to establish and
         designate any further Series, the Trustees have established and
         designated twenty seven (27) Series: Janus Fund, Janus Balanced Fund,
         Janus Contrarian Fund, Janus Core Equity Fund, Janus Enterprise Fund,
         Janus Federal Tax-Exempt Fund, Janus Flexible Income Fund, Janus Global
         Life Sciences Fund, Janus Global Technology Fund, Janus Global
         Opportunities Fund, Janus Government Money Market Fund, Janus Growth
         and Income Fund, Janus High-Yield Fund, Janus Institutional Cash
         Reserves Fund, Janus Mercury Fund, Janus Mid Cap Value Fund, Janus
         Money Market Fund, Janus Olympus Fund, Janus Orion Fund, Janus Overseas
         Fund, Janus Risk-Managed Stock Fund, Janus Short-Term Bond Fund, Janus
         Small Cap Value Fund, Janus Tax-Exempt Money Market Fund, Janus Twenty
         Fund, Janus Venture Fund, and Janus Worldwide Fund. The Shares of such
         Series and classes thereof and any Shares of any further Series or
         classes thereof that may from time to time be established and
         designated by the Trustees shall have the following relative rights and
         preferences (unless the Trustees otherwise determine with respect to
         some further Series or classes thereof at the time of establishing and
         designating the same):


         IN WITNESS WHEREOF, the undersigned has set her hand and seal this 30th
day of September, 2004.


                                           /s/ Kelley Abbott Howes
                                           -------------------------------------
                                           Kelley Abbott Howes, Secretary




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STATE OF COLORADO            )
                             )    ss.
CITY AND COUNTY OF DENVER    )

         BEFORE ME, the undersigned authority, on this day personally appeared
Kelley Abbott Howes, Secretary of Janus Investment Fund, who, being by me first
duly sworn, stated on her oath that the foregoing document is true and correct
and that she executed the same for the purposes and consideration therein
expressed and in the capacity therein stated.

         GIVEN UNDER MY HAND AND SEAL OF OFFICE this 30th day of September,
2004.



My Commission Expires:                      /s/ Lisa A. Neison
     6.22.07                                ------------------------------------
---------------------                       Notary Public




[Notary Seal]



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