Certification Pursuant to 18 U.S.C. Section 1350, as Adopted Pursuant to
Section 906 of the Sarbanes-Oxley Act of 2002

In connection with the attached Report of John Hancock Patriot Preferred
Dividend Fund (the "registrant") on Form N-CSR to be filed with the Securities
and Exchange Commission (the "Report"), each of the undersigned officers of
the registrant does hereby certify that, to the best of such officer's
knowledge:

1. The Report fully complies with the requirements of Section 13(a) or 15(d)
of the Securities Exchange Act of 1934; and

2. The information contained in the Report fairly presents, in all material
respects, the financial condition and results of operations of the registrant
as of, and for, the periods presented in the Report.


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James A. Shepherdson
President and Chief Executive Officer

Dated:  July 21, 2004


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Richard A. Brown
Senior Vice President and Chief Financial Officer

Dated:  July 21, 2004


A signed original of this written statement, required by Section 906, has been
provided to the registrant and will be retained by the registrant and
furnished to the Securities and Exchange Commission or its staff upon request.