A prospective randomised controlled clinical trial began in 1989 on 126 patients with superficial transitional cell carcinoma of the bladder (pTa-pT1, grades 1-3) to compare the efficacy of adjuvant topical mitoxantrone after transurethral resection versus no further treatment. 62 patients received no further treatment, 64 patients received weekly 20 mg mitoxantrone intravesically for 6 weeks after differentiated TUR of all visible tumours. The endpoint of the study was any progression of stage or grade or further recurrences. The median follow up was 29 months-the minimum follow up was 24 months. The percentage of recurrences (25.8 versus 23.4), the recurrence rate (1.2 versus 0.9), the overall disease free interval and the tumour progression rate showed no statistically significant differences (P > 0.05 Mantel-Cox test). Only the comparison of time to recurrence in tumours with recurrences showed a statistically significant difference, with a longer disease free interval for the TUR plus mitoxantrone group (P = 0.016 Mantel-Cox test).