The difficulty in treating carcinoma that has infiltrated into the wall of the urinary bladder lies not so much in eradicating the tumor as in diverting the flow of urine into some other suitable channel. The carcinomatous bladder must be removed at all costs if the patient is to be spared needless suffering. Operations that alter the position of the ureters have several disadvantages. The advantages of nephrostomy are here illustrated by four case histories. The operation is simple, does the least damage to the kidneys, and affords an easy approach to the kidneys if treatment becomes necessary; urine can be collected easily with least discomfort to the patient, no other organs need to be used as reservoirs, and there is no need to disturb the ureters.