REPORT OF INDEPENDENT PUBLIC ACCOUNTANTS This is a copy of the audit report previously issued by Arthur Andersen LLP in connection with Aspen Technology, Inc.'s filing on Form 10-K for the year ended June 30, 2001. This audit report has not been reissued by Arthur Andersen LLP in connection with this filing on Form 10-K. The consolidated balance sheets as of June 30, 2000 and 2001 and the consolidated statements of operations, stockholders' equity and cash flows for the years ended June 30, 1999 and 2000 referred to in this report have not been included in the accompanying financial statements or schedule. To Aspen Technology, Inc.: We have audited the accompanying consolidated balance sheets of Aspen Technology, Inc. (a Delaware corporation) and subsidiaries as of June 30, 2000 and 2001, and the related consolidated statements of operations, stockholders' equity and comprehensive income (loss) and cash flows for each of the three years in the period ended June 30, 2001. These consolidated financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on these consolidated financial statements based on our audits. We conducted our audits in accordance with auditing standards generally accepted in the United States. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. An audit includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements. An audit also includes assessing the accounting principles used and significant estimates made by management, as well as evaluating the overall financial statement presentation. We believe that our audits provide a reasonable basis for our opinion. In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the financial position of Aspen Technology, Inc. and subsidiaries as of June 30, 2000 and 2001, and the results of their operations and their cash flows for each of the three years in the period ended June 30, 2001 in conformity with accounting principles generally accepted in the United States. Boston, Massachusetts August 3, 2001 Arthur Andersen LLP Report of Independent Public Accountants 71