In all, 165 862 PSA tests were performed on 84 669 men, and over a third of men aged > or = 50 years had at least one PSA test. Men aged < 50 years accounted for 12.9% of first tests. The proportion of tests from primary care increased from 47.2% in 1993 to 67.0% in 1999. The mean age of men tested once decreased from 65.6 to 61.9 years (P trend < 0.001) and the proportion with an elevated PSA level also declined during the period. Repeat testing increased with PSA level (P < 0.001) but 29.4% of men with a PSA level of < or = 4 ng/mL also had repeat testing. Raised PSA values were more common from hospital than primary care (32.4% vs 20.6%, P < 0.001) and in older men. Test rates varied 100-fold across general practices, a finding not explained by sociodemographic factors, but one which reflects differential adherence to national guidelines, suggesting that general practitioners are key targets for attempting to rationalise the use of the PSA test.