[logo] PIONEER
       Investments(R)







                                                 March 4, 2005

VIA ELECTRONIC TRANSMISSION

Securities and Exchange Commission
Judiciary Plaza
450 Fifth Street, NW
Washington, DC  20549

Re:  Pioneer Mid Cap Value Fund (the "Fund")
     (File Nos. 33-34801 and 811-06106)
     CIK No. 0000863334

Ladies and Gentlemen:

     Pursuant to Rule 497(j) under the  Securities  Act of 1933,  as amended,  I
certify  that the forms of  prospectuses  relating to the offering of the Fund's
Class A, Class B, Class C, Class R, Class Y and  Investor  Class  shares and the
multi-class statement of additional information that would have been filed under
paragraph (c) of Rule 497 do not differ from those  contained in Post- Effective
Amendment  No.  25 to the  Fund's  registration  statement  on Form  N-1A  filed
electronically (Accession No. 0001016964-05-000076) on February 25, 2005.

     If you have any questions  concerning the foregoing  certification,  please
contact me at (617) 422-4947.
                                                 Very truly yours,


                                                 /s/ Jon-Luc Dupuy
                                                 Jon-Luc Dupuy



cc:  Mr. David C. Phelan








Pioneer Investment Management, Inc.
60 State Street
Boston, MA  02109-1820



 "Member of the UniCredito Italiano Banking Group, Register of Banking Groups."