Twenty-seven consecutive patients with locally extensive or metastatic urothelial cancer, primarily bladder, were given cis-diamminedichloroplatinum (II) (DDP) at a dose of 70 mg/m2 every three weeks. All patients had hydration and mannitol-induced diuresis initiated before administration of DDP. Nine patients (33%) had a partial response; 12 (45%) remained stable for an average duration of six months. Responders had a significantly greater survival than nonresponders. Although severe nephrotoxicity did not occur, patients with either a solitary or obstructed kidney were at greater risk of an increase in the serum creatinine during therapy.