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                                                                    EXHIBIT 31.1

                            SECTION 302 CERTIFICATION

I, Kenneth I. Moch, Chief Executive Officer, certify that:

    1.   I have reviewed this quarterly report on Form 10-Q of Alteon Inc.;

    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 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 the 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 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 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
         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.

Dated: November 13, 2003             /s/ Kenneth I. Moch
                                     -------------------------------------------
                                     Kenneth I. Moch
                                     President and Chief Executive Officer