In the Department of Urology, University of Freiburg, West Germany extracorporeal piezoelectric shock wave lithotripsy (EPL) has been used in the treatment of urinary and biliary stones since November 1987. The first 85 treatments (in 71 patients) for renal stones were evaluated with regard to complications and side effects. There was no need for any anesthesia. Urinary obstruction was observed in 12% of the cases. Aside from the urinary obstruction and urosepsis (2%) no serious complications were seen. Endourological auxiliary measures were applied in 32% (27% prophylactically). The temporary glomerular damage which appeared in some patients vanished within 6 days after treatment. Because of possible asymptomatic ureteral obstruction a close follow up by ultrasound is recommended. EPL was found to be a useful method of treatment for renal calculi with few side effects.