It has been claimed, though not scientifically proven, that early diagnosis and treatment of prostate cancer reduce cancer-related mortality. The aim of the present study is to assess the frequency of PSA-based screening in Norwegian primary health care. In 1998 Norwegian general practitioners and occupational physicians reported their use of diagnostic PSA (prostatic specific antigen) testing in men without urinary symptoms (opportunistic PSA screening). There were considerable variations between counties and an increasing tendency to screen 60% of physicians performed opportunistic PSA screening; however, 55% only "sometimes". Men over 75 were frequently tested. The results reflect the scientific uncertainty regarding opportunistic PSA screening. PSA screening as an element of health care policy can only be recommended if cancer-related mortality is reduced by early diagnosis and treatment of prostate cancer.