A total of 431 eligible patients with solitary, primary or recurrent stages Ta and T1 transitional cell carcinoma of the bladder was included in a randomized multicenter trial to compare a single intravesical instillation of 80 mg. epirubicin with water given immediately after resection, with respect to the disease-free interval and recurrence rate. The interval to initial recurrence was significantly better in favor of the epirubicin group. After a mean followup of 2 years it became evident that the recurrence rate after a single epirubicin instillation was decreased by nearly half with the same trend being found in all subgroups examined. Toxicity was mainly restricted to bladder irritation in plus or minus 10% of the cases. Pathology review brought considerable changes in T category from stages T1 to Ta (53%). Changes in grade were less pronounced but nevertheless important.