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                                                                   Exhibit 4(oo)

                              FORM OF AMENDMENT TO

                               JANUS ASPEN SERIES

                        INVESTMENT SUB-ADVISORY AGREEMENT

                      RISK-MANAGED LARGE CAP CORE PORTFOLIO

         THIS AMENDMENT is made this 1st day of May, 2004, between JANUS CAPITAL
MANAGEMENT LLC, a Delaware limited liability company ("Janus"), and ENHANCED
INVESTMENT TECHNOLOGIES, LLC, a Delaware limited liability company ("INTECH").

                               W I T N E S S E T H

         WHEREAS, Janus and INTECH are parties to an Investment Sub-Advisory
Agreement on behalf of Risk-Managed Large Cap Core Portfolio (the "Portfolio"),
a series of Janus Aspen Series, a Delaware statutory trust (the "Trust"), dated
December 10, 2002 (the "Agreement");

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

         WHEREAS, pursuant to Section 11 of the Agreement, any amendment to the
Agreement is subject to 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 1940 Act) of the Trust or Janus, INTECH or
their affiliates, and (ii) if required by applicable law, by the affirmative
vote of a majority of the outstanding voting securities of the Portfolio (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; and

         WHEREAS, the name of Risk-Managed Large Cap Core Portfolio has been
changed to Risk-Managed Core Portfolio effective May 1, 2004;

         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.       All references to "Risk-Managed Large Cap Core Portfolio"
shall be replaced with "Risk-Managed Core Portfolio."

         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 and any prior amendments, contains the
entire understanding and the full and

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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 may be contemporaneously executed in two or
more counterparts, each of which shall be deemed an original but all of which
together shall constitute one and the same instrument.

         IN WITNESS WHEREOF, the parties have caused their duly authorized
officers to execute this Amendment as of the date first above written.

                                       JANUS CAPITAL MANAGEMENT LLC

                                       By: _____________________________________
                                           Kelley A. Howes, Vice President and
                                           General Counsel

                                       ENHANCED INVESTMENT TECHNOLOGIES, LLC

                                       By: _____________________________________
                                       Name: ___________________________________
                                       Title: __________________________________