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 Investment Trust III (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 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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Maureen R. Ford
Chairman, President and Chief Executive Officer

Dated: June 25, 2003



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Richard A. Brown
Senior Vice President and Chief Financial Officer

Dated: June 25, 2003

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.