Intravesical bacillus Calmette-Guerin (BCG) has been shown to be effective therapy and prophylaxis against recurrent tumor in patients with superficial bladder cancer (stages O and A), including carcinoma in situ. Tice-Chicago strain BCG was used to treat superficial transitional cell carcinoma of the bladder in 24 patients between July, 1985 and June, 1987. A variety of different BCG treatment regimens have been used that vary in intensity. In general, treatment results have been more favorable with intensive regimens. However, the toxicity also has been subustantially greater with intensive regimens. The optimal regimen has yet to be determined. Our treatment regimen of 120mg. Tice-Chicago strain BCG weekly for 6 weeks and then monthly for 3 months was well tolerated. 23 patients had a complete response and one had a tumor recurrence at 18 months follow-up, resulting in 96%of response rate. Side effects during of shortly after treatment were minor and self-limiting in the majority of patients (fever, bladder irritability and hematuria). This experience supports the efficacy of BCG as a cost effective, well-tolerated treatment modality for patients with superficial transitional cell carcinoma of the bladder.