Cisplatin, 50-150 mg in a maximum concentration of 1 mg/ml, was administered intravesically each week to 24 patients with multiple, recurrent carcinoma in situ and/or bladder tumors confined to the mucosa and lamina propria. All patients had a history of multiple transurethral resections and four had received prior chemotherapy. Response was evaluated by urinary cytology, cystoscopy, and biopsy. In a total of 237 weekly doses, toxicities included mild dysuria, pruritus, rash and in one patient, acute anaphylaxis. Only three (13%) patients were classified as achieving complete remission. Cisplatin, in the dose and schedule employed, is ineffective in controlling superficial bladder cancer.