The results of a double blind prospective study comparing the chemoprophylactic effects of adriamycin and mitomycin C and two modes of instillation (early: 6 hours following transurethral resection; late: 7-14 days later) for superficial carcinoma of the bladder are presented herein. Since the minimum follow up is over 5 years, the effects on tumor progression and mortality achieved by each of the 4 arms of the protocol were also evaluated. Concerning tumor recurrence, early instillation of mitomycin and overall early instillation therapy achieved significantly better results (p < 0.01). No differences, however, were observed relative to tumor progression or mortality.