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                                                                    Exhibit 31.1

                                  CERTIFICATION


I, Leonard S. Schwartz, certify that:

        1.      I have reviewed this quarterly report on Form 10-Q of Aceto
                Corporation (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 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)) and internal control over financial reporting (as
                defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) 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)      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
                        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 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 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:  May  10, 2007

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