The use of topical agents in the treatment and prophylaxis of transitional cell carcinoma of the bladder is well described. Several physicians have reported the use of these materials in the upper urinary tract for treatment of transitional cell carcinoma. We present our treatment protocol using mitomycin C as topical therapy following endoscopic resection of superficial urothelial tumors of the renal pelvis or ureter. A total of 7 patients was treated during the last 4 years. No systemic side effects due to perfusion with mitomycin C occurred. We believe that our treatment method provides a safe means of delivering topical agents to the upper urinary tract and suggest its use when such treatment is believed to be necessary.