AMENDMENT

                                                                 EXHIBIT 4(x)

                                    AMENDMENT

     This Amendment is made as of January 31, 2000, by and between Janus
Investment Fund, a Massachusetts business trust (the "Trust") on behalf of Janus
Global Life Sciences Fund (the "Fund"), and Janus Capital Corporation, a
Colorado corporation ("JCC"). The Trust and JCC are collectively referred to
herein as the "Parties."

     WHEREAS, the Trust and JCC are parties to an Investment Advisory Agreemen
dated July 1, 1997 (hereinafter referred to as the "Agreement"); and

     WHEREAS, the Parties desire to amend the Agreement as set forth in greater
detail below; and

     WHEREAS, pursuant to Section 12 of the Agreement, any amendment to the
Agreement is subject to the approval by (i) a majority of the Trustees,
including a majority of the Trustees who are not interested persons (as that
phrase is defined in Section 2(a)(19) of the 0000 Xxx) of JCC and, if required
by applicable law, (ii) by the affirmative vote of a majority of the outstanding
voting securities of the Fund (as that phrase is defined in Section 2(a)(42) of
the 1940 Act);

     WHEREAS, the Parties have obtained Trustee approval as set forth above and
the Parties agree that a shareholder vote is not required to amend the
Agreement;

     NOW THEREFORE, in consideration of the premises and of the mutual
agreements set forth below, the Parties agree to amend the Agreement as follows:

     1.   Section 4 of the Agreement is hereby deleted and replaced in its
          entirety by the following:

          "4. Compensation. The Trust shall pay to JCC for its investment
              advisory services a fee, calculated and payable for each day that
              this Agreement is in effect, of 1/365 of 0.65% of the daily
              closing net asset value of the Fund (1/366 of 0.65% of the daily
              closing net asset value of the Fund in a leap year). The fee shall
              be paid monthly."

     2.   The Parties acknowledge that the Agreement, as amended, remains in
          full force and effect as of the date of this Amendment, and that this
          Amendment, together with the Agreement, contain the entire
          understanding and the full and complete agreement of the Parties and
          supercedes and replaces any prior understandings and agreements among
          the Parties respecting the subject matter hereof.

     3.   This Amendment to the Agreement may be contemporaneously executed in
          one or more counterparts, each of which shall be deemed an original
          but all of which together




shall constitute one and the same instrument.

     4.   Each of the undersigned is duly authorized to sign this Amendment on
          behalf of the respective Parties.

     IN WITNESS WHEREOF, the Parties have executed this Amendment to the
Agreement as of the date first above written.

JANUS CAPITAL CORPORATION



BY:    /s/ Xxxxxx X. Goodbarn
NAME:  XXXXXX X. GOODBARN
TITLE: VICE PRESIDENT

JANUS INVESTMENT FUND



BY :     /s/ Xxxxxx X. Xxxxxx
NAME:    XXXXXX X. XXXXXX
TITLE:   PRESIDENT