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                                                                    EXHIBIT 31.1

                               CAMBREX CORPORATION
     CERTIFICATION PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002
                            (18 U.S.C. SECTION 1350)

I, John R. Leone, certify that:

      1. I have reviewed this quarterly report on Form 10-Q/A of Cambrex
         Corporation;

      2. Based on my knowledge, this quarterly 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 quarterly report;

      3. Based on my knowledge, the financial statements, and other financial
         information included in this quarterly 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 quarterly 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 quarterly report is being prepared;

          b) [Reserved]

          c) 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

          d) 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.

                                                /s/ John R. Leone
                                                --------------------------------
                                                John R. Leone, President
                                                Chairman of the Board and
                                                Chief Executive Officer

Date:  April 29, 2005

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