Percutaneous nephrostomy can be accomplished by using a trocar-cannula assembly without resorting to serial dilations of the tube tract or utilizing stiff catheters. After puncture the trocar is removed and a catheter inserted through the cannula; then the cannula is removed. A large number of these procedures have been performed and have been found to be simple and quite safe. The method is able to provide nephrostomy drainage in virtually any case of ureteral obstruction or leak, and can be used to drain perinephric fluid collections as well. Antegrade pyelography precedes trocar puncture; puncture is most easily guided by fluoroscopy. The technique is described in detail; indications, applications, complications, and contraindications are outlined.