To determine the value of prostatic markers for prostate cancer, serum prostatic acid phosphatase (PAP), prostate specific antigen (PSA) and gamma-Seminoprotein (gamma-Sm) were measured in 81 patients with benign prostatic hypertrophy and in 12 patients with incidental prostatic cancer. gamma-Sm was the most sensitive but the least specific of the three markers. Large prostate glands, especially hyper-glandular type tended to be associated with high gamma-Sm levels in our study. Patients with acute urinary retention, acute prostatitis and necrosis also showed positive markers. Out of 12 patients with incidental cancer, 5 patients had more than 2 elevated markers. Four patients with poorly differentiated adenocarcinoma failed to show increased markers.