<PAGE>
MFS/SUN LIFE SERIES TRUST
Conservative Growth Series
SUPPLEMENT TO THE CURRENT PROSPECTUS
The description of portfolio managers under the "Management of the Series
Investment Adviser" section is hereby revised as follows:
John D. Laupheimer, Jr., a Senior Vice President of MFS, and Mitchell D. Dynan,
a Vice President of MFS, have been portfolio managers of the series since
January 1, 1993 and January 1, 1995, respectively and have been employed as
portfolio managers by the Adviser since 1981 and 1986, respectively.
The date of this Supplement is September 1, 1998.
