Intravesical instillation of anticancer agents is one of the most effective methods for treating superficial bladder cancer. We evaluated the effects of including 4'-Epi-Adriamycin, a derivative of Adriamycin, in intravesical instillation chemotherapy. Thirty-five patients with superficial bladder tumors were treated with 4'-Epi-Adriamycin. The patients received 2 courses of 3 consecutive daily instillations of 50-80 mg 4'-Epi-Adriamycin dissolved in 30 ml of physiological saline, with an interval of 4 days. Of the 33 cases which could be fully evaluated, complete regression was observed in 4 cases and partial regression (greater than 50%) in 14 cases, showing an effectiveness rate of 55%. Side effects such as pollakisuria and miction pain occurred in 9 cases. The rate of effectiveness of this treatment was approximately equivalent to the results that we reported using Adriamycin and the occurrence and degree of side effects were lower.