A total of 84 patients with superficial transitional cell carcinoma underwent transurethral resection of bladder tumor. All patients had stage pTa or pT1 transitional cell carcinoma or carcinoma in situ without other concurrent malignancies. The patients were assigned to three treatment groups: I. Control group-transurethral resection (TUR-BT) discontinued within the study. II. Oral BCG group-TUR-BT plus BCG (Moreau). III. Intravesical BCG group-TUR-BT plus BCG. Of 9 patients in the control group, 8 (89%) experienced tumor recurrence during a mean follow-up of 20 months. Of the 33 patients in the oral BCG group, 13 patients (39.3%) had recurrence during a mean follow-up of 39 months. Of the 42 patients in the intravesical group, 8 patients (19%) had recurrence in a 30-month mean follow-up. The incidence of complications was higher in the intravesical (33.4%) than in the oral BCG group (24.2%). These results showed that intravesical BCG is a more effective immunotherapy; however, oral BCG can be utilized in patients who do not accept intravesical BCG administration.