[logo] PIONEER Investments(R)







                                                 March 3, 2006

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 form of  prospectuses  relating to the  offering of the Fund's
Class A, B and C prospectus, Class R prospectus, Class Y prospectus and Investor
Class shares  prospectus  that would have been filed under paragraph (c) of Rule
497 do not differ from those contained in Post-Effective  Amendment No.26 to the
Fund's  registration  statement  on Form N-1A  filed  electronically  (Accession
No.0000869356-06-000014) on February 28, 2006.

     If you have any questions concerning the foregoing  certification,  please
contact me at (617) 517-8909.
                                                 Very truly yours,


                                                 /s/ Nancy Fanning
                                                     Nancy Fanning

                                                     Legal Product Manager




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."