Percutaneous techniques were successful in removing stones from 101 (92%) of 110 kidneys attempted. Ultrasonic lithotripsy was used on 80 kidneys in 74 patients with stones 5-38 mm in diameter. The most common complication was incomplete disintegration with retained stone fragments. Twenty patients were treated by direct stone extraction, either by a stone basket or forceps. The average hospitalization for percutaneous stone removal of 10 days was not significantly different from that for open nephrolithotomy. However, patients undergoing percutaneous stone removal had only a 3-10 day convalescence after hospital discharge before returning to normal activity.