A total of 76 patients with transitional cell carcinoma of the bladder were prospectively monitored with simultaneous serum value estimations of tumor polypeptide antigen (TPA), tumor-associated trypsin inhibitor (TATI), carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), beta-human chorionic gonadotropin (beta-HCG), prostatic specific antigen (PSA), squamous cell carcinoma antigen (SCC), and CA 19-9 in different stages and phases of their disease. In locally advanced disease positive values were noted for TATI in 22/28 patients (78.5%), for TPA in 17/28 (60.7%), for CA 19-9 in 10/28 (35.7%), for CEA 11/28 (39.2%), for beta-HCG in 3/28 (10.7%), for PSA in 6/28 (21.4%), for SCC in 6/28 (21.4%), and for AFP in 0/28. In metastatic disease elevated levels were observed for TATI in 43/48 patients (89.5%), for TPA in 41/48 (85.4%), for CA 19-9 in 19/48 (39.5%), for CEA in 20/48 (41.6%), for beta-HCG in 6/48 (12.5%), for PSA in 7/48 (14.5%), for SCC in 8/48 (16.6%), and for AFP in 1/48 (2.1%). In metastatic disease TATI and TPA values were significantly modified in patients with complete remission and TATI, TPA, and CA 19-9 in patients with partial remission and nonresponders. In T2-T4-N0M0 tumors, TPA, TATI, CA 19-9, and CEA were significantly increased in nonresponders. In patients with complete remission, a change in serum TATI, TPA, and CA 19-9 levels cannot be evidenced with the available numbers. The concurrent determination of TATI and TPA in T2-T4N0M0 tumors and TATI, TPA, and CA 19-9 in generalized disease could predict the response to chemotherapy. This study indicates that only the determination of TATI and TPA and in some degree the CA 19-9 is a potential tool for monitoring the efficacy of treatment.