The value of screening for prostate cancer remains unclear. Although digital rectal examination, transrectal ultrasono-graphy, and determination of serum prostate-specific antigen levels may lead to early detection of a malignancy, these procedures have never been shown to reduce disease-specific mortality from prostate cancer. Unfortunately, several potential errors found in uncontrolled trials may suggest benefit from screening where none exists. Only a large, randomized, controlled clinical study demonstrating decreased mortality from prostate cancer can prove that screening is beneficial. Until such a study is performed, patients should be informed of both the potential benefits and the risks of screening and treatment. [J Natl Cancer Inst 83:329–335, 1991]