Clinical studies of carcinoembryonic antigen (CEA) in prostate fluid were performed on 121 men; 29 patients with prostate cancer, 65 with benign prostatic hypertrophy, 10 with prostatitis and 17 without any prostatic diseases. The CEA level in prostate fluid in the prostate cancer group was significantly higher than that in any other group. However, it could not demonstrate any particular advantage when compared with the prostate specific antigen (PSA) in serum. Additional research was done comparing the sensitivity and specificity of CEA level in prostate fluid in the population with slightly elevated PSA level (3.0-14.9 ng/ml). The sensitivity and the specificity were 82% and 83%, respectively. These findings suggest the usefulness of the measurement of prostate fluid CEA as an adjunctive tool in the diagnosis of prostate cancer in the population with a slightly elevated PSA level.