To evaluate the effects of bladder instillation chemotherapy of anticancer agents with OK-432 intradermal injection (group A) in preventing postoperative recurrence of bladder carcinoma, a randomized controlled study with intravesical instillation chemotherapy of anticancer agents (group B) as the reference standard was performed. As the anticancer agents, pepleomycin (PEP) was usually used at a concentration of 30 mg/30 ml physiological saline. OK-432 injection dose was gradually increased from 0.5 KE to 5.0 KE and maintenance dose was decided by local skin reactions. There were no differences in the patient's background factors between group A (22 cases) and group B (17 cases). The no-recurrence rate of bladder carcinoma was similar in the two groups, but the no-recurrence rate for the virgin tumor or the stage T0 cases was higher in group B. On the other hand, the values for the recurrent cases or the stage T1,2 cases was higher in group A. The SU-PS skin reaction as an immunological response was significantly higher in group A. There were no severe side effects derived from anticancer bladder instillation or OK-432 injection.