Exhibit 12(a)


                                  Certification

I, Jason C.S. Chang, the Chief Executive Officer of ASE Test Limited, or the
registrant, certify that:

         1. I have reviewed this annual report on Form 20-F of the registrant;

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

         3. Based on my knowledge, the financial statements, and other
financial information included in this annual 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 annual 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) [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
         period covered by the 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: June 30, 2004
                                                /s/ Jason C.S. Chang
                                               ---------------------------------
                                               Name:    Jason C.S. Chang
                                               Title:   Chief Executive Officer


                                    12(a)-1