February 6, 1996
VIA ELECTRONIC TRANSMISSION
Securities and Exchange Commission
File Desk
Judiciary Plaza
450 Fifth Street, NW
Washington, DC 20549
Re: Pioneer Mid-Cap Fund (the "Fund")
(formerly Pioneer Three)
File Nos. 2-79140 and 811-3564
CIK No. 0000706155
Ladies and Gentlemen:
Pursuant to Rule 497(j) under the Securities Act of 1933, this
letter certifies that the Prospectus and Statement of Additional Information
that would have been required to be filed under paragraph (c) of Rule 497 does
not differ from that contained in Post-Effective Amendment No. 21, and that the
text of the Post -Effective Amendment has been filed electronically, Accession
No.
0000706155-96-000003, on February 1, 1996.
If you have any questions concerning the foregoing or the
attachments, please call the undersigned or Elizabeth Watson collect at (617)
742-7825.
Very truly yours,
/s/Eunice R. Simmons
Eunice R. Simmons
EDGAR Compliance Associate
cc: Ms. Elizabeth Watson
Mses. Rajotte/Alves
Joseph P. Barri, Esq.
Mr. Mark Goshko, Esq.
