PURPOSE: We define bacillus Calmette-Guerin (BCG) refractory, high risk, superficial bladder cancer. MATERIALS AND METHODS: A total of 93 patients received a 6-week induction course of BCG. They were evaluated for response after 3 and 6 months. Half of the patients received monthly maintenance BCG for 2 years and half did not. In both groups the initial responses to BCG at 3 and 6 months were correlated with subsequent tumor recurrence and progression. RESULTS: Of the 93 cases 57% were negative for tumor at 3 months and 43% had residual tumor resected. At 6 months 80% of the patients were tumor-free and 20% had persistent or recurrent tumor. Maintenance BCG did not decrease tumor recurrence further than induction BCG. Subsequent tumor-free interval during 24 months of followup were best predicted by response to BCG after 6 months. CONCLUSIONS: A minimum treatment and followup time of 6 months is required to identify high risk, superficial bladder tumors as truly BCG refractory.