A total of 10 patients with histologically proved carcinoma in situ of the bladder had remission of tumor after topical chemotherapy with doxorubicin hydrochloride for 24 months. Of the 10 patients 3 suffered new areas of carcinoma in situ 9 to 12 months after termination of intravesical chemotherapy. Furthermore, 1 of these 3 patients had a distal ureteral tumor. Fibrosis of the submucosal tissue was observed in every patient but a decrease in bladder capacity was observed in only 1 with prior radiotherapy.