<PAGE>
SUPPLEMENT DATED AUGUST 27, 1999
TO PROSPECTUS DATED MAY 1, 1999
OF
CONSERVATIVE PORTFOLIO
MODERATE PORTFOLIO
AGGRESSIVE PORTFOLIO
PORTFOLIOS OF
MORGAN STANLEY DEAN WITTER STRATEGIC ADVISER FUND, INC.
P.O. BOX 2798
BOSTON, MASSACHUSETTS
02208-2798
---------------------
The Prospectus is hereby amended and supplemented to reflect a change in the
voluntary fee waivers for the Conservative Portfolio. Accordingly, the first
paragraph of the footnote on page 8 is hereby deleted and replaced with the
following:
* THE FEES FOR THE PORTFOLIOS SHOWN IN THE TABLE ABOVE ARE THE
HIGHEST THAT COULD BE CHARGED. THIS TABLE DOES NOT SHOW THE
EFFECTS OF MSDW INVESTMENT MANAGEMENT'S VOLUNTARY FEE WAIVERS
AND/OR EXPENSE REIMBURSEMENTS. MSDW INVESTMENT MANAGEMENT HAS
VOLUNTARILY AGREED TO REDUCE ITS ADMINISTRATION FEE AND/OR
REIMBURSE THE PORTFOLIOS SO THAT TOTAL ANNUAL EXPENSES,
INCLUDING EXPENSES ATTRIBUTABLE TO INVESTMENT IN UNDERLYING
FUNDS, WILL NOT EXCEED 0.80% FOR THE CLASS A SHARES AND 1.05%
FOR THE CLASS B SHARES OF THE CONSERVATIVE PORTFOLIO; 0.90% FOR
THE CLASS A SHARES AND 1.15% FOR THE CLASS B SHARES OF THE
MODERATE PORTFOLIO; AND 1.10% FOR THE CLASS A SHARES AND 1.35%
FOR THE CLASS B SHARES OF THE AGGRESSIVE PORTFOLIO.
------------------------
PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE