['To evaluate the performance of percentage free/total prostate-specific antigen (f/tPSA) as a screening tool for prostate cancer, and to assess the impact of prostatic inflammation on f/tPSA.', 'Men aged 50-65 years were invited for prostate cancer screening. Biopsies were taken from men with a tPSA of > or = 4 ng/mL, together with those with a tPSA of 1.1-3.99 ng/mL and a f/tPSA of < or = 20%. Histological evidence of prostate cancer, acute inflammation, chronic inflammation, and benign prostatic tissue were noted in biopsy cores, together with the associated f/tPSA values.', 'The cancer detection rate was 4.3% (33/773). Evidence of inflammation was found in about half (87/175) of those biopsied. Men with acute inflammation (27/175, 15%) had significantly lower serum f/tPSA values (mean 13.4%) than those with chronic inflammation (mean 16.6%, P = 0.002) and benign prostatic tissue (mean 15.7%, P = 0.034), but were similar to men with prostate cancer (mean 15.3%, P = 0.315).'] Is incidental acute prostatic inflammation associated with a lower percentage of free prostate-specific antigen than other benign conditions of the prostate : a prospective screening study?