The usefulness of prostate specific antigen (PSA) in screening for prostatic carcinoma was studied in 262 inpatients of the department of internal medicine. All patients underwent a rectal digital examination and determination of PSA by the Tandem-E method (Hybritech). The plan was to perform biopsies if there were suspicious findings on the rectal examination or if the PSA value was more than 10 ng/ml. The PSA values were < or = 4 ng/ml in 219 patients (83.6%), > 4 to 10 ng/ml in 27 patients (10.3%) and > 10 ng/ml in 16 men (6.1%). In consideration of the severity of disease which limited life expectancy we did not perform a biopsy on 37.5% of the patients with PSA > 10 ng/ml. 7 patients with prostatic carcinoma were found. Their PSA values varied between 11.2 and 875 ng/ml. The cancer detection rate was highest for the combination of a suspicious rectal examination and a PSA value > 10 ng/ml (70%).