Page 98 of 134

                                                                       EXHIBIT 4


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                                                                Page 99 of 134

                    CERTIFICATION OF CHIEF EXECUTIVE OFFICER
                           PURSUANT TO SECTION 302 OF
                         THE SARBANES-OXLEY ACT OF 2002

I, K.Y. Ho, principal executive officer of ATI Technologies Inc. (the "issuer"),
certify that:

1.       I have reviewed this annual report on Form 40-F of the issuer;

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 issuer as of, and for, the periods presented in this report;

4.       The issuer'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 issuer
         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 issuer, 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 issuer'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

                  (c) Disclosed in this report any change in the issuer'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
                  issuer's internal control over financial reporting; and

5.       The issuer's other certifying officer and I have disclosed, based on
         our most recent evaluation of internal control over financial
         reporting, to the issuer's auditors and the audit committee of the
         issuer'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
                  issuer's ability to record, process, summarize and report
                  financial information; and

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                                                                Page 100 of 134


                  (b) Any fraud, whether or not material, that involves
                  management or other employees who have a significant role in
                  the issuer's internal control over financial reporting.

Date: January 16, 2004   By:     //K.Y. Ho//
                             --------------------------------------------------
                                 K.Y. Ho
                                 Chairman and Chief Executive Officer







<PAGE>
                                                                Page 101 of 134


                    CERTIFICATION OF CHIEF FINANCIAL OFFICER
                         PURSUANT TO SECTION 302 OF THE
                           SARBANES-OXLEY ACT OF 2002

I, Terry Nickerson, principal financial officer of ATI Technologies Inc. (the
"issuer"), certify that:

1.       I have reviewed this annual report on Form 40-F of the issuer;

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 issuer as of, and for, the periods presented in this report;

4.       The issuer'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 issuer
         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 issuer, 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 issuer'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

                  (c) Disclosed in this report any change in the issuer'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
                  issuer's internal control over financial reporting; and

5.       The issuer's other certifying officer and I have disclosed, based on
         our most recent evaluation of internal control over financial
         reporting, to the issuer's auditors and the audit committee of the
         issuer'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
                  issuer's ability to record, process, summarize and report
                  financial information; and

<PAGE>
                                                                Page 102 of 134


                  (b) Any fraud, whether or not material, that involves
                  management or other employees who have a significant role in
                  the issuer's internal control over financial reporting.

Date: January 16, 2004   By:       //Terry Nickerson//
                             --------------------------------------------------
                                   Terry Nickerson
                                   Senior Vice President, Finance and
                                   Chief Financial Officer