Urokinase was used to clear occluded silastic central venous catheters in 14 pediatric patients. The catheters, which had been placed into a neck vein and tunnelled out through the skin of the anterior chest wall, were being used for either long-term parenteral nutrition or chemotherapy. Occluded catheters that could not be cleared by simple flushing with heparinized saline were filled with a solution of urokinase, which was left in place for 2 hours before the catheter was flushed a second time. Twenty-one occluded catheters were managed in this way over a period of 14 months. There were no allergic reactions or bleeding complications. Twelve of the 21 occluded catheters were immediately cleared. Three catheters ruptured during attempted flushing maneuvers but were patent after repair. Two catheters remained partially occluded. Only four catheters were removed because of persistent occlusion. When simpler techniques fail, urokinase instillation appears a safe and effective alternative to the more common practice of removing occluded central venous catheters in children.