FROM THE TRUSTEES                               [PHOTO OF JOHN A. HILL AND
                                                    GEORGE PUTNAM, III]


Dear Shareholder:

As you have already learned from the proxy statement we sent you a few weeks
ago, we are seeking your vote for the merger of Putnam Investment Grade
Municipal Income Trust III into its sister fund, Putnam Investment Grade
Municipal Income Trust II.

It is the opinion of your Trustees and Putnam Investment Management that the
consolidation would benefit the shareholders of both funds. The funds'
investment objectives and policies are virtually identical and the merger is a
key element in a plan to make the combined, larger fund more attractive to
potential investors both by issuing additional preferred shares to enhance
current income potential and by creating a larger trading market for the
combined fund's common shares. Of course, there can be no guarantee that these
steps would have the intended effect.

We urge you to consider the proposal carefully by reviewing the proxy statement
and cast your vote either by mailing the completed proxy card or via the
Internet at www.proxyweb.com/Putnam.

Respectfully yours,


/s/ John A. Hill                         /s/ George Putnam, III
----------------                         ----------------------

John A. Hill                             George Putnam, III
Chairman of the Trustees                 President of the Funds
June 20, 2001