THE PIONEER GROUP, INC.
60 State Street
Boston, MA 02109-1820
617-742-7825
[Pioneer logo]
February 2, 1999
VIA ELECTRONIC TRANSMISSION
Securities and Exchange Commission
Judiciary Plaza
450 Fifth Street, NW
Washington, DC 20549
Re: Pioneer Mid-Cap Fund (the "Fund")
(File Nos. 2-79140 and 811-07525)
CIK No. 0000706155
Ladies and Gentlemen:
Pursuant to Rule 497(j) under the Securities Act of 1933, as
amended, I certify that the form of the Fund's multiclass prospectus that would
have been filed under paragraph (c) of Rule 497 do not differ from that
contained in Post-Effective Amendment No. 26 to the Fund's registration
statement on Form N-1A filed electronically (Accession No. 0001016964-99-000013)
on January 27, 1999.
If you have any questions about this certification, please contact
me at (617) 422-4966 (collect).
Very truly yours,
/s/ Mark Pietkiewicz
Mark Pietkiewicz
Senior Legal Product Manager
cc: Mr. Joseph P. Barri
Mr. David C. Phelan
Mr. Timothy F. Silva
Ms. Victoria J. Regan
g:\edgar\final\99\md497j.txt
