EXHIBIT 23.1 INDEPENDENT AUDITORS' CONSENT We consent to the incorporation by reference in Registration Statement No. 333-45049 of OSI Systems Inc. and Subsidiaries on Form S-8 of our report dated September 11, 1998, appearing in this Annual Report on Form 10-K of OSI Systems Inc. and Subsidiaries for the year ended June 30, 1998. DELOITTE & TOUCHE LLP Los Angeles, California September 11, 1998.