Prostate cancer is now the leading cancer in men and the second most common cause of death from cancer in men. There is little information on PSA use in Canada. The study documented the patient PSA workload in Ontario, Canada, from 1988 to 1995. The study also assessed the feasilibility of obtaining patient-specific data from laboratories to conduct longitudinal follow-up studies. A questionnaire was sent to all laboratories in Ontario that carry out clinical testing. Responses were obtained from 272 of 292 laboratories of which 45 indicated that they carry out PSA testing 'on site'. There were 14 laboratories suitable for participation in additional research which accounted for 117,000 PSA test per year, roughly one-third the provincial workload. Overall, the amount of PSA testing exceeded expectations. Because of the large amount of PSA testing being carried out in Ontario, there is a need for public and government policy on PSA utilization, and for guidelines to physicians and patients about the test.