Three cases of cyclophosphamide (CPM)-induced transitional cell carcinoma (TCC) of the bladder are reported. A 36-year-old female (case 1) and a 63-year-old male (case 2) received CPM at total doses of 104 g and 100 g, respectively, for the therapy of Wegener's granulomatosis. A 50-year-old female (case 3) received CPM at a dose of 57 g for the therapy of recurrent breast cancer. They visited our institute with the chief complaint of macrohematuria. In all cases, cystoscopy revealed bladder tumor with hemorrhagic cystitis. They underwent transurethral resection of bladder tumor. Histological examination revealed grade 2 TCC in cases 1 and 2 and grade 3 TCC in case 3. All patients underwent intravesical instillation of Mitomycin C with or without hyperthermia. Including our 3 cases, 17 cases of CPM-induced bladder tumor have been reported in the Japanese literature.