AMENDMENT TO SUB-ADVISORY AGREEMENT This Amendment to the Sub-Advisory Agreement, dated August 6, 2004 (the "Agreement"), by and between Pioneer Investment Management, Inc. (the "Adviser") and Ibbotson Associates Advisors, LLC (the "Sub-Adviser") is...

                       AMENDMENT TO SUB-ADVISORY AGREEMENT

     This  Amendment to the  Sub-Advisory  Agreement,  dated August 6, 2004 (the
"Agreement"), by and between Pioneer Investment Management, Inc. (the "Adviser")
and Ibbotson Associates Advisors, LLC (the "Sub-Adviser") is effective as of May
12, 2005.

                                   WITNESSETH:

     WHEREAS,  pursuant  to the  terms  of  Agreement,  the  Adviser  serves  as
investment  manager  to  series  (each  a  "Fund")  of  Pioneer  Ibbotson  Asset
Allocation   Series  (the  "Trust")  and  the  Sub-Adviser  acts  as  investment
sub-adviser of each Fund;

     WHEREAS,  the Adviser and Sub-Adviser  desire to amend the Agreement to add
an additional Fund to Annex A of the Agreement;

     NOW THEREFORE, in consideration of the mutual promises set forth below, the
Adviser and the Sub-Adviser hereby agree to amend the Agreement as follows:

     Annex A of the  Agreement is hereby  replaced in its entirety  with the new
     Annex A attached hereto.

     Except  as  provided  herein,  the terms and  conditions  contained  in the
Agreement shall remain in full force and effect.


     IN WITNESS WHEREOF,  this Amendment to the Agreement has been executed by a
duly authorized  representative  of each of the parties hereto as of the date of
the Amendment first set forth above.

PIONEER INVESTMENT MANAGEMENT, INC.


_________________________________
By:
Title:


IBBOTSON ASSOCIATES ADVISORS, LLC


By: _________________________________
Name:
Title:






Annex A
(As amended on May 12, 2005)

Pioneer Ibbotson Moderate Allocation Fund
Pioneer Ibbotson Growth Allocation Fund
Pioneer Ibbotson Aggressive Allocation Fund
Pioneer Ibbotson Conservative Allocation Fund