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EX-99.CERT
MFS/SUN LIFE SERIES TRUST
CERTIFICATION PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT
I, Richard M. Hisey, certify that:
1. I have reviewed this report on Form N-CSR of MFS/Sun Life Series Trust;
2. Based on my knowledge, this report does not contain any untrue statement of
a material fact or omit to state a material fact necessary to make the
statements made, in light of the circumstances under which such statements
were made, not misleading with respect to the period covered by this
report;
3. Based on my knowledge, the financial statements, and other financial
information included in this report, fairly present in all material
respects the financial condition, results of operations, changes in net
assets, and cash flows (if the financial statements are required to include
a statement of cash flows) of the registrant as of, and for, the periods
presented in this report;
4. The registrant's other certifying officers and I are responsible for
establishing and maintaining disclosure controls and procedures (as defined
in Rule 30a-3(c) under the Investment Company Act of 1940) for the
registrant and have:
a. designed such disclosure controls and procedures, or caused such
disclosure controls and procedures to be designed under our
supervision, to ensure that material information relating to the
registrant, including its consolidated subsidiaries, is made known to
us by others within those entities, particularly during the period in
which this report is being prepared;
b. evaluated the effectiveness of the registrant's disclosure controls
and procedures and presented in this report our conclusions about the
effectiveness of the disclosure controls and procedures as of a date
within 90 days prior to the filing date of this report based on such
evaluation (the "Evaluation Date"); and
c. disclosed in this report any change in the registrant's internal
control over financial reporting that occurred during the
registrant's most recent fiscal half-year (the registrant's second
fiscal half-year in the case of an annual report) that has materially
affected, or is reasonably likely to materially affect, the
registrant's internal control over financial reporting; and
5. The registrant's other certifying officers and I have disclosed to the
registrant's auditors and the audit committee of the registrant's board of
directors (or persons performing the equivalent functions):
a. all significant deficiencies and material weaknesses in the design or
operation of internal control over financial reporting which are
reasonably likely to adversely affect the registrant's ability to
record, process, summarize, and report financial information; and
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b. any fraud, whether or not material, that involves management or other
employees who have a significant role in the registrant's internal
control over financial reporting.
Date: February 23, 2004 RICHARD M. HISEY
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Richard M. Hisey
Treasurer (Principal Financial Officer
and Accounting Officer)
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MFS/SUN LIFE SERIES TRUST
CERTIFICATION PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT
I, Robert J. Manning, certify that:
1. I have reviewed this report on Form N-CSR of MFS/Sun Life Series Trust;
2. Based on my knowledge, this report does not contain any untrue statement of
a material fact or omit to state a material fact necessary to make the
statements made, in light of the circumstances under which such statements
were made, not misleading with respect to the period covered by this
report;
3. Based on my knowledge, the financial statements, and other financial
information included in this report, fairly present in all material
respects the financial condition, results of operations, changes in net
assets, and cash flows (if the financial statements are required to include
a statement of cash flows) of the registrant as of, and for, the periods
presented in this report;
4. The registrant's other certifying officers and I are responsible for
establishing and maintaining disclosure controls and procedures (as defined
in Rule 30a-3(c) under the Investment Company Act of 1940) for the
registrant and have:
a. designed such disclosure controls and procedures, or caused such
disclosure controls and procedures to be designed under our
supervision, to ensure that material information relating to the
registrant, including its consolidated subsidiaries, is made known to
us by others within those entities, particularly during the period in
which this report is being prepared;
b. evaluated the effectiveness of the registrant's disclosure controls
and procedures and presented in this report our conclusions about the
effectiveness of the disclosure controls and procedures as of a date
within 90 days prior to the filing date of this report based on such
evaluation (the "Evaluation Date"); and
c. disclosed in this report any change in the registrant's internal
control over financial reporting that occurred during the
registrant's most recent fiscal half-year (the registrant's second
fiscal half-year in the case of an annual report) that has materially
affected, or is reasonably likely to materially affect, the
registrant's internal control over financial reporting; and
5. The registrant's other certifying officers and I have disclosed to the
registrant's auditors and the audit committee of the registrant's board of
directors (or persons performing the equivalent functions):
a. all significant deficiencies and material weaknesses in the design or
operation of internal control over financial reporting which are
reasonably likely to adversely affect the registrant's ability to
record, process, summarize, and report financial information; and
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b. any fraud, whether or not material, that involves management or other
employees who have a significant role in the registrant's internal
control over financial reporting.
Date: February 23, 2004 ROBERT J. MANNING
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Robert J. Manning
President (Principal Executive Officer)