<PAGE>

                                                                    EXHIBIT 31.1

                                  CERTIFICATION

I, Donald R. Sellers, certify that:

    1.       I have reviewed this Form 10-Q of SciClone Pharmaceuticals, Inc.
             (the registrant);

    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 and cash flows of the registrant as of, and for, the
             periods presented in this report;

    4.       The registrant's other certifying officer(s) and I are responsible
             for establishing and maintaining disclosure controls and procedures
             (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) 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 the end of the period covered by this
                  report based on such evaluation; 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 quarter (the registrant's
                  fourth fiscal quarter 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 officer(s) and I have disclosed,
             based on our most recent evaluation of internal control over
             financial reporting, 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

                  (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: October 31, 2003                                /s/ Donald R. Sellers
                                                 -------------------------------
                                                        Donald R. Sellers
                                                     Chief Executive Officer