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                                                                    Exhibit 31.1

                      CHIEF EXECUTIVE OFFICER CERTIFICATION

I, Leonard S. Schwartz, Chairman, President and Chief Executive Officer of Aceto
Corporation, certify that:

        1.      I have reviewed this Quarterly Report on Form 10-Q of Aceto
                Corporation (the "Registrant");

        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 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)      designed such internal control over financial reporting,
                        or caused such internal control over financial reporting
                        to be designed under our supervision, to provide
                        reasonable assurance regarding the reliability of
                        financial reporting and the preparation of financial
                        statements for external purposes in accordance with U.S.
                        generally accepted accounting principles; and

                c)      evaluated the effectiveness of the Registrant's
                        disclosure controls and procedures and presented in this
                        Quarterly 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 Quarterly Report any change in the
                        Registrant's internal control over financial reporting
                        that occurred during the Registrant's first 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 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.

Dated: November 9, 2006

/s/ Leonard S. Schwartz
-------------------------
Chairman, President and Chief Executive Officer
(Principal Executive Officer)