To determine if serum prostate-specific antigen (PSA) can identify those patients harboring an organ-confined prostate cancer prior to treatment for symptomatic benign prostatic hyperplasia (BPH), we examined retrospectively the preoperative serum PSA level for two groups of men. Group 1 consisted of 187 consecutive patients with a histologic diagnosis of BPH as determined from complete pathologic analysis of the transurethral resection of the prostate (TURP) specimen. Group 2 included 198 consecutive patients with histologically confirmed organ-confined prostate cancer as determined from step-section analysis of the retropubic radical prostatectomy specimen. The median serum PSA value for group 1 was 3.9 ng/ml (range 0.2-55 ng/ml), whereas the median serum PSA level for group 2 was 5.9 ng/ml (range 0.4-58 ng/ml). Although this difference was statistically significant (p