Extracorporeal shock-wave lithotripsy is a technique for pulverizing urinary stones in vivo by focusing hydraulic shock waves on the stone (1-3). This innovative form of therapy is the by-product of a long-term research program by the Dornier System GmbH (Friedrichafen, Federal Republic of Germany) on the effect of shock waves. A stimulus for the initiation of this program was the contrecoup damage that occurred in gas-filled satellites when they were struck by micrometeorites. At a social gathering, a physician, who was the wife of one of the engineers working on the shock-wave project, suggested that shock waves could be used