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                                                                 Exhibit 4(aaaa)
                               JANUS ASPEN SERIES

                          INVESTMENT ADVISORY AGREEMENT

                           WORLDWIDE GROWTH PORTFOLIO

      THIS INVESTMENT ADVISORY AGREEMENT (the "Agreement") is made this 1st day
of July, 2004, as amended this 1st day of February, 2006, between JANUS ASPEN
SERIES, a Delaware statutory trust (the "Trust"), and JANUS CAPITAL MANAGEMENT
LLC, a Delaware limited liability company ("JCM").

                              W I T N E S S E T H:

      WHEREAS, the Trust is registered as an open-end management investment
company under the Investment Company Act of 1940, as amended (the "1940 Act"),
and has registered its shares for public offering under the Securities Act of
1933, as amended (the "1933 Act"); and

      WHEREAS, the Trust is authorized to create separate funds, each with its
own separate investment portfolio of which the beneficial interests are
represented by a separate series of shares; one of such funds created by the
Trust being designated as the Worldwide Growth Portfolio (the "Fund"); and

      WHEREAS, the Trust and JCM deem it mutually advantageous that JCM should
be appointed as the investment adviser to the Fund.

      NOW, THEREFORE, the parties agree as follows:

      1. Appointment. The Trust hereby appoints JCM as investment adviser and
manager with respect to the Fund for the period and on the terms set forth in
this Agreement. JCM hereby accepts such appointment and agrees to render the
services herein set forth, for the compensation herein provided.

      2. Investment Advisory Services. JCM shall determine the securities or
other assets to be purchased, sold or held and shall place orders for the
purchase or sale of such securities or other assets with brokers, dealers or
others. JCM shall furnish continuous advice and recommendations to the Fund, and
have authority to act with respect thereto, as to the acquisition, holding, or
disposition of any or all of the securities or other assets which the Fund may
own or contemplate acquiring from time to time. JCM shall give due consideration
to the investment policies and restrictions and the other statements concerning
the Fund in the Trust Instrument, bylaws, and registration statements under the
1940 Act and the 1933 Act, and to the provisions of the Internal Revenue Code,
as amended from time to time, applicable to the Fund as a regulated investment
company and as a funding vehicle for variable insurance contracts. In addition,
JCM shall cause its officers to attend meetings and furnish oral or written
reports, as the Trust may reasonably require, in order to keep the Trustees and
appropriate officers of the Trust fully informed as to the condition of the
investment portfolio of the Fund.

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      3. Other Services. JCM is hereby authorized (to the extent the Trust has
not otherwise contracted) but not obligated (to the extent it so notifies the
Trustees at least 60 days in advance), to perform (or arrange for the
performance by affiliates of) the management and administrative services
necessary for the operation of the Fund. JCM is specifically authorized, on
behalf of the Trust, to conduct relations with custodians, depositories,
transfer and pricing agents, accountants, attorneys, underwriters, brokers and
dealers, corporate fiduciaries, insurance company separate accounts, insurers,
banks and such other persons in any such other capacity deemed by JCM to be
necessary or desirable. JCM shall generally monitor and report to Fund officers
the Fund's compliance with investment policies and restrictions as set forth in
the currently effective prospectus and statement of additional information
relating to the shares of the Fund under the 1933 Act. JCM shall make reports to
the Trustees of its performance of services hereunder upon request therefor and
furnish advice and recommendations with respect to such other aspects of the
business and affairs of the Fund as it shall determine to be desirable. JCM is
also authorized, subject to review by the Trustees, to furnish such other
services as JCM shall from time to time determine to be necessary or useful to
perform the services contemplated by this Agreement.

      4. Obligations of Trust. The Trust shall have the following obligations
under this Agreement:

         (a)      to keep JCM continuously and fully informed as to the
                  composition of its investment portfolio and the nature of all
                  of its assets and liabilities from time to time;

         (b)      to furnish JCM with a certified copy of any financial
                  statement or report prepared for it by certified or
                  independent public accountants and with copies of any
                  financial statements or reports made to its shareholders or to
                  any governmental body or securities exchange;

         (c)      to furnish JCM with any further materials or information which
                  JCM may reasonably request to enable it to perform its
                  function under this Agreement; and

         (d)      to compensate JCM for its services and reimburse JCM for its
                  expenses incurred hereunder in accordance with the provisions
                  hereof.

      5. Compensation. The Trust shall pay to JCM for its investment advisory
services a monthly base fee of 1/12 of 0.60% of the average daily closing net
asset value of the Fund, adjusted by a performance fee as set forth in Schedule
A. For any period less than a month during which this Agreement is in effect,
the base fee shall be prorated according to the proportion which such period
bears to a full month of 28, 29, 30 or 31 days, as the case may be.

      6. Expenses Borne by JCM. In addition to the expenses which JCM may incur
in the performance of its investment advisory functions under this Agreement,
and the expenses which it may expressly undertake to incur and pay under other
agreements with the Trust or

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otherwise, JCM shall incur and pay the following expenses relating to the Fund's
operations without reimbursement from the Fund:

         (a)      Reasonable compensation, fees and related expenses of the
                  Trust's officers and its Trustees, except for such Trustees
                  who are not "interested persons," as defined in the 1940 Act,
                  of JCM; and

         (b)      Rental of offices of the Trust.

      7. Expenses Borne by the Trust. The Trust assumes and shall pay all
expenses incidental to its organization, operations and business not
specifically assumed or agreed to be paid by JCM pursuant to Sections 3 and 6
hereof, including, but not limited to, investment adviser fees; any
compensation, fees, or reimbursements which the Trust pays to its Trustees who
are not "interested persons," as defined in the 1940 Act, of JCM; compensation
of the Fund's custodian, transfer agent, registrar and dividend disbursing
agent; legal, accounting, audit and printing expenses; administrative, clerical,
recordkeeping and bookkeeping expenses; brokerage commissions and all other
expenses in connection with execution of portfolio transactions (including any
appropriate commissions paid to JCM or its affiliates for effecting exchange
listed, over-the-counter or other securities transactions); interest; all
federal, state and local taxes (including stamp, excise, income and franchise
taxes); costs of stock certificates and expenses of delivering such certificates
to purchasers thereof; expenses of local representation in Delaware; expenses of
shareholders' meetings and of preparing, printing and distributing proxy
statements, notices, and reports to shareholders; expenses of preparing and
filing reports and tax returns with federal and state regulatory authorities;
all expenses incurred in complying with all federal and state laws and the laws
of any foreign country applicable to the issue, offer, or sale of shares of the
Fund, including, but not limited to, all costs involved in the registration or
qualification of shares of the Fund for sale in any jurisdiction, the costs of
portfolio pricing services and compliance systems, and all costs involved in
preparing, printing and mailing prospectuses and statements of additional
information to Fund shareholders; and all fees, dues and other expenses incurred
by the Trust in connection with the membership of the Trust in any trade
association or other investment company organization. To the extent that JCM
shall perform any of the above described administrative and clerical functions,
including transfer agency, registry, dividend disbursing, recordkeeping,
bookkeeping, accounting and blue sky monitoring and registration functions, and
the preparation of reports and returns, the Trust shall pay to JCM compensation
for, or reimburse JCM for its expenses incurred in connection with, such
services as JCM and the Trust shall agree from time to time, any other provision
of this Agreement notwithstanding.

      8. Termination. This Agreement may be terminated at any time, without
penalty, by the Trustees of the Trust, or by the shareholders of the Fund acting
by vote of at least a majority of its outstanding voting securities, provided in
either case that sixty (60) days advance written notice of termination be given
to JCM at its principal place of business. This Agreement may be terminated by
JCM at any time, without penalty, by giving sixty (60) days advance written
notice of termination to the Trust, addressed to its principal place of
business. The Trust agrees that, consistent with the terms of the Trust
Instrument, the Trust shall cease to use the name "Janus" in connection with the
Fund as soon as reasonably practicable following any termination of this

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Agreement if JCM does not continue to provide investment advice to the Fund
after such termination.

      9. Assignment. This Agreement shall terminate automatically in the event
of any assignment of this Agreement.

      10. Term. This Agreement shall continue in effect until February 1, 2007,
unless sooner terminated in accordance with its terms, and shall continue in
effect from year to year thereafter only so long as such continuance is
specifically approved at least annually by (a) the vote of a majority of the
Trustees of the Trust who are not parties hereto or interested persons of any
such party, cast in person at a meeting called for the purpose of voting on the
approval of the terms of such renewal, and (b) either the Trustees of the Trust
or the affirmative vote of a majority of the outstanding voting securities of
the Fund. The annual approvals provided for herein shall be effective to
continue this Agreement from year to year if given within a period beginning not
more than ninety (90) days prior to February 1 of each applicable year,
notwithstanding the fact that more than three hundred sixty-five (365) days may
have elapsed since the date on which such approval was last given.

      11. Amendments. This Agreement may be amended by the parties only if such
amendment is specifically approved (i) by 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 any party to this Agreement 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).

      12. Other Series. The Trustees shall determine the basis for making an
appropriate allocation of the Trust's expenses (other than those directly
attributable to the Fund) between the Fund and the other series of the Trust.

      13. Limitation of Personal Liability. All the parties hereto acknowledge
and agree that all liabilities of the Trust arising, directly or indirectly,
under this Agreement, of any and every nature whatsoever, shall be satisfied
solely out of the assets of the Fund and that no Trustee, officer or holder of
shares of beneficial interest of the Trust shall be personally liable for any of
the foregoing liabilities. The Trust Instrument describes in detail the
respective responsibilities and limitations on liability of the Trustees,
officers and holders of shares of beneficial interest of the Trust.

      14. Limitation of Liability of JCM. JCM shall not be liable for any error
of judgment or mistake of law or for any loss arising out of any investment or
for any act or omission taken with respect to the Trust, except for willful
misfeasance, bad faith or gross negligence in the performance of its duties, or
by reason of reckless disregard of its obligations and duties hereunder and
except to the extent otherwise provided by law. As used in this Section 14,
"JCM" shall include any affiliate of JCM performing services for the Trust
contemplated hereunder and directors, officers and employees of JCM and such
affiliates.

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      15. Activities of JCM. The services of JCM to the Trust hereunder are not
to be deemed to be exclusive, and JCM and its affiliates are free to render
services to other parties. It is understood that trustees, officers and
shareholders of the Trust are or may become interested in JCM as directors,
officers and shareholders of JCM, that directors, officers, employees and
shareholders of JCM are or may become similarly interested in the Trust, and
that JCM may become interested in the Trust as a shareholder or otherwise.

      16. Certain Definitions. The terms "vote of a majority of the outstanding
voting securities," "assignment" and "interested persons" when used herein,
shall have the respective meanings specified in the 1940 Act, as now in effect
or hereafter amended, and the rules and regulations thereunder, subject to such
orders, exemptions and interpretations as may be issued by the Securities and
Exchange Commission under said Act and as may be then in effect.

      17. Governing Law. This Agreement shall be construed in accordance with
the laws of the State of Colorado (without giving effect to the conflicts of
laws principles thereof) and the 1940 Act. To the extent that the applicable
laws of the State of Colorado conflict with the applicable provisions of the
1940 Act, the latter shall control.

      This Agreement shall supercede all prior investment advisory agreements
entered into between JCM and the Trust, on behalf of the Fund.

      IN WITNESS WHEREOF, the parties have caused their duly authorized officers
to execute this Investment Advisory Agreement as of the amended date and year
first above written.

                             JANUS CAPITAL MANAGEMENT LLC

                             By: /s/ David R. Martin
                                 -------------------
                                     David R. Martin, Chief Financial Officer
                                     and Executive Vice President

                             JANUS ASPEN SERIES

                             By: /s/ Kelley A. Howes
                                 -------------------
                                     Kelley A. Howes, President and Chief
                                     Executive Officer

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                                   SCHEDULE A
                             PERFORMANCE ADJUSTMENT

      Beginning with the Base Fee payable for February 2006 and in month 13 from
the amended date of this Agreement, the Base Fee shall be adjusted monthly based
upon the investment performance of the Fund's Service Shares ("Class") in
relation to the cumulative investment record of the Fund's benchmark, the MSCI
World Index (the "Index"), over the "Performance Period" (such adjustment being
referred to herein as the "Performance Adjustment"). The "Performance Period" is
defined as the shorter of (a) the period from the date of this Agreement through
the end of the month for which the fee is being calculated, and (b) the 36 month
period preceding the end of the month for which the fee is being calculated.

      The Performance Adjustment shall be calculated by subtracting the
investment record of the Index from the investment performance of the Class. If
there is less than a 0.50% difference (plus or minus) between the investment
performance of the Class and the investment record of the Index, the Fund pays
JCM the Base Fee with no adjustment. If the difference between the investment
performance of the Class and the investment record of the Index is 0.50% or
greater during any Performance Period, the Base Fee will be subject to an upward
or downward performance adjustment of 1/12 of 0.0125% for every full 0.50%
increment by which the Class outperforms or underperforms the Index. The maximum
percentage used in calculating the Performance Adjustment (positive or negative)
in any month is 1/12 of 0.15%. The Performance Adjustment is applied against the
Fund's average daily net assets during the Performance Period.

      For purposes of computing the Base Fee and the Performance Adjustment, net
assets are averaged over different periods (average daily net assets during the
relevant month for the Base Fee versus average daily net assets during the
Performance Period for the Performance Adjustment). The Base Fee is calculated
and accrued daily. The Performance Adjustment is calculated monthly in arrears
and is accrued evenly each day throughout the month. The investment advisory fee
is paid monthly in arrears.

      The average daily net asset value of the Fund, or any class thereof, shall
be determined in the manner set forth in the Trust's Amended and Restated Trust
Instrument, Bylaws and registration statement, each as may be amended from time
to time.

      The investment performance of the Class will be the sum of:

      (1) the change in the Class's net asset value ("NAV") per share during the
Performance Period; plus

      (2) the value of the Class's cash distributions per share accumulated to
the end of the Performance Period; plus

      (3) the value of capital gains taxes per share paid or payable on
undistributed realized long-term capital gains accumulated to the end of the
Performance Period;

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expressed as a percentage of the Class's NAV per share at the beginning of the
Performance Period. For this purpose, the value of distributions per share of
realized capital gains, of dividends per share paid from investment income and
of capital gains taxes per share paid or payable on undistributed realized
long-term capital gains shall be treated as reinvested in shares of the Class at
the NAV in effect at the close of business on the record date for the payment of
such distributions and dividends and the date on which provision is made for
such taxes, after giving effect to such distributions, dividends and taxes.

      The investment record of the Index will be the sum of:

      (1) the change in the level of the Index during the Performance Period;
plus

      (2) the value, computed consistently with the Index, of cash distributions
made by companies whose securities comprise the Index accumulated to the end of
the Performance Period; expressed as a percentage of the Index level at the
beginning of the Performance Period. For this purpose, cash distributions on the
securities which comprise the Index shall be treated as reinvested in the Index
at least as frequently as the end of each calendar quarter following the payment
of the dividend.

      The Trustees have initially designated the Class to be used for purposes
of determining the Performance Adjustment. From time to time, the Trustees may,
by vote of the Trustees of the Trust voting in person, including a majority of
the Trustees who are not parties to this Agreement or "interested persons" (as
defined in the 1940 Act) of any such parties, determine that a class of shares
of the Fund other than the Class is the most appropriate for use in calculating
the Performance Adjustment. If a different class of shares ("Successor Class")
is substituted in calculating the Performance Adjustment, the use of that
Successor Class of shares for purposes of calculating the Performance Adjustment
may apply to the entire Performance Period so long as such Successor Class was
outstanding at the beginning of such period. If the Successor Class of shares
was not outstanding for all or a portion of the Performance Period, it may only
be used in calculating that portion of the Performance Adjustment attributable
to the period during which such Successor Class was outstanding and any prior
portion of the Performance Period shall be calculated using the class of shares
previously designated.

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