The epidemiology, histopathology, diagnosis and staging, and treatment of prostate cancer are reviewed. Prostate cancer, one of the most common malignancies occurring in men over age 50, will strike an estimated 103,000 men in the United States in 1989. More than 95% of prostatic tumors are adenocarcinomas. Tumors are graded on the basis of their degree of differentiation. Most afflicted men initially complain of difficulty in starting the urinary stream and of urinary bleeding, dribbling, and retention. Urinary obstruction may be present in advanced disease, and anemia, anorexia, and bone pain are common in metastatic disease. Prostatectomy and irradiation are used to treat disease localized to the prostate; the prognosis for such patients is good. Survival is diminished in cases of locally advanced and metastatic disease. Symptomatic metastatic disease is treated by hormonal manipulation through orchiectomy and administration of exogenous estrogens (diethylstilbestrol), luteinizing hormone-releasing hormone analogs (leuprolide and goserelin), and antiandrogens (cyproterone acetate, flutamide, and others). Some 70-80% of patients respond to hormonal therapy for periods of up to three years. After relapse occurs, salvage hormonal therapies (aminoglutethimide and ketoconazole) may be attempted to prolong survival. Fluorouracil, doxorubicin, mitomycin, cisplatin, cyclophosphamide, methotrexate, and estramustine have also been administered, with mixed results. Once relapse occurs in prostate cancer patients after initial hormonal therapy, the response to salvage hormonal or cytotoxic therapy is minimal; in the future, total androgen blockade and methods of decreasing drug resistance may be used to prolong survival.