EXHIBIT 23.1 CONSENT OF INDEPENDENT ACCOUNTANTS We hereby consent to the incorporation by reference in the Registration Statements on Form S-8 (No.'s 333-34272, 333-34270 and 333-82680) of Cabot Microelectronics Corporation of our report dated October 21, 2003, except for paragraph 2 of Note 7, as to which the date is November 24, 2003, relating to the financial statements and financial statement schedule which appears in this Form 10-K. /s/ PRICEWATERHOUSECOOPERS LLP Chicago, Illinois December 10, 2003