Kidney stones may be removed without using a surgical incision by a combination of techniques and skills recently developed in the fields of urology and radiology. Percutaneous access to the kidney is established under fluoroscopic control. A guide wire placed into the renal pelvis allows a nephroscope to be inserted and the collecting system visualized. A long hollow metal probe is advanced through the nephroscope and placed in contact with the stone. This probe conducts the ultrasonic energy. The stone absorbs the energy and breaks into fine granules which are evacuated by suction. Percutaneous lithotomy was performed upon 300 of 302 consecutive patients bearing stones which required removal. Targeted calculi were successfully removed from 97 per cent of these patients. Eighty-one per cent had complete stone removal at the primary procedure; 57 patients required additional percutaneous manipulations under local or general anesthesia. The previous 100 patients with kidney stones underwent surgical removal of the calculi. Complications associated with percutaneous stone removal included postoperative fever, delayed urinary bleeding, ureteral edema, symptomatic urinary extravasation and water intoxication. Only 16 patients with complications required prolonged hospitalization or readmission. No complications required surgical management; no deaths occurred. Anesthetic times were similar for both groups, averaging 152 +/- 4 (S. E. M.) minutes for PL and 193 +/- 8 minutes for SL. Hospital recovery days averaged 5.7 +/- 0.3 for PL and 8.4 +/- 0.5 for SL (p less than 0.01). Associated costs averaged $7,203 +/- 255 for PL and $8,849 +/- 660 for SL (p less than 0.01). The number of narcotic administrations per patient (days one to five postoperatively) averaged 9.9 +/- 0.7 for the PL group and 16.8 +/- 0.8 for the SL group (p less than 0.01). The average patient in the PL group felt capable of full activity 2.0 +/- 0.2 weeks after stone removal, whereas no patient who experienced previous SL recalls a recovery period of less than three weeks (p less than 0.01). Most upper urinary tract calculi may be removed cost-effectively using a percutaneous approach. Patients may expect a rapid convalescence with diminished pain.