Background: In 1998, there were 1,218 deaths in Chile caused by prostate cancer. This figure results in a death rate of 16.6 per 100,000 males for this disease. Aim: To assess the prevalence of prostate cancer in the Seventh Region of Chile. Material and methods: A probabilistic sample of 327 males aged 40 to 59 years old was studied. In all, a codified questionnaire was applied, a digital rectal examination was performed and a blood sample was drawn to measure prostate specific antigen. All digital rectal examinations were performed by the same observer. Patients with an abnormal rectal examination or prostate specific antigen were subjected to a prostatic biopsy under ultrasound guidance. Results: In 14 subjects, the digital rectal examination was considered abnormal and in seven, prostate specific antigen was over 4 ng/ml. All subjects with elevated prostate specific antigen had an abnormal rectal examination. In three of the 14 subjects, the biopsy showed a well differentiated adenocarcinoma. All three were aged over 50 years old. The resulting calculated prevalence of prostate cancer was 9.2 per 1,000 males (CI 4.2-14.1). Conclusions: the cost effectiveness of screening for early diagnosis of prostate cancer must be calculated, to decide its incorporation in preventive medical examinations (Rev Méd Chile 2001; 129: 1305-10)