<PAGE>
SUPPLEMENT TO PROSPECTUS
OF
DEAN WITTER VARIABLE INVESTMENT SERIES
DATED MAY 1, 1998
ON MARCH 24, 1998, MORGAN STANLEY, DEAN WITTER, DISCOVER & CO., THE PARENT
COMPANY OF THE FUND'S INVESTMENT MANAGER, TRANSFER AGENT AND DISTRIBUTOR, WAS
RENAMED MORGAN STANLEY DEAN WITTER & CO. The current Prospectus reflects the new
name.
ON JUNE 22, 1998, DEAN WITTER VARIABLE INVESTMENT SERIES WAS RENAMED MORGAN
STANLEY DEAN WITTER VARIABLE INVESTMENT SERIES. All references in the current
Prospectus to "Dean Witter Variable Investment Series" or "the Fund" apply to
Morgan Stanley Dean Witter Variable Investment Series.
ON JUNE 22, 1998, THE DEAN WITTER FUNDS WERE RENAMED THE "MORGAN STANLEY
DEAN WITTER FUNDS." All references in the current Prospectus to the "Dean Witter
Funds" apply to the Morgan Stanley Dean Witter Funds.
ON JUNE 22, 1998, DEAN WITTER INTERCAPITAL INC., THE FUND'S INVESTMENT
MANAGER, WAS RENAMED MORGAN STANLEY DEAN WITTER ADVISORS INC. All references in
the current Prospectus to "Dean Witter InterCapital Inc.," "InterCapital" or
"the Investment Manager" apply to Morgan Stanley Dean Witter Advisors Inc.
ON MARCH 24, 1998, DEAN WITTER TRUST FSB, THE FUND'S TRANSFER AGENT, WAS
RENAMED MORGAN STANLEY DEAN WITTER TRUST FSB. The current Prospectus reflects
the new name.
ON JUNE 22, 1998, DEAN WITTER DISTRIBUTORS INC., THE FUND'S DISTRIBUTOR, WAS
RENAMED MORGAN STANLEY DEAN WITTER DISTRIBUTORS INC. All references in the
current Prospectus to "Dean Witter Distributors Inc.," "the Distributor" or
"Distributors" apply to Morgan Stanley Dean Witter Distributors Inc.
ON JUNE 22, 1998, DEAN WITTER SERVICES COMPANY INC., A SUBSIDIARY OF
INTERCAPITAL THAT PERFORMS CERTAIN ADMINISTRATIVE SERVICES FOR THE FUND, WAS
RENAMED MORGAN STANLEY DEAN WITTER SERVICES COMPANY INC. All references in the
current Prospectus to "Dean Witter Services Company, Inc." or "DWSC" apply to
Morgan Stanley Dean Witter Services Company Inc.
June 22, 1998
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