Bacille Calmette-Guerin (BCG) is the most effective therapy for CIS of the bladder. Although several series have shown a decrease in recurrence and progression of T1 tumor, this effect is temporary. More than one half of patients with T1 tumors treated with BCG will progress over the longterm. A second course of BCG is indicated after an initial complete response. There is no definitive answer regarding the efficacy of maintenance therapy or the optimum dose of BCG. Randomized trials are needed to address these issues in a more conclusive manner. Phase III trials have shown that mitomycin C can be as effective as BCG in the management of papillary tumors; however, BCG is more effective in patients with CIS and high-risk superficial tumors.