BACKGROUND Prostate cancer is the second most common cause of death from cancer in men in the United States. Digital rectal examination is the oldest and most commonly used screening test for prostate cancer, but as yet there are no studies which demonstrate its effectiveness. METHODS A case-control study was conducted among members of a large health maintenance organisation to estimate the effect of screening digital rectal examination on mortality from prostate cancer. 150 men, aged 40-84 when cancer was diagnosed, who developed fatal prostate cancer, and 299 male controls matched for age who did not die from prostate cancer were studied. A history of screening digital rectal examination during the 10 years before the date on which cancer was-diagnosed was determined from medical records. RESULTS A similar proportion of men who died from prostate cancer and controls had undergone at least one screening digital rectal examination during the 10 year interval (odds ratio = 0.84, 95% confidence interval 0.48 to 1.46). Similar results were obtained when a shorter interval (such as five years before diagnosis) during which screening histories were evaluated was considered, or in analyses in which men with a history of benign prostatic hypertrophy were excluded. CONCLUSIONS The data suggest that screening digital rectal examination does not reduce mortality from prostate cancer to any appreciable degree.