A known radioimmunometric prostate-specific antigen (PSA) test based on monoclonal antibodies, as well as a new PSA-ELISA utilizing 4 monoclonal antibodies directed against different epitopes of PSA were compared in a clinical evaluation. For the investigation, collectives of patient sera from patients with independently diagnosed prostatic carcinoma (PCA) as well as benign prostatic hyperplasia (BPH) were employed. The results of the evaluation demonstrated that although the PSA immunoradiometric test and the PSA-ELISA yielded different numerical values for PSA serum concentrations, they possess comparable diagnostic sensitivities as well as specificities. The nonradioactive PSA-ELISA could therefore substitute the PSA-IRMA in a clinical routine diagnostic of PCA.