All stools passed on the first 3 days after extracorporeal shock-wave lithotripsy of gallbladder stones in 21 patients were collected and examined for the presence of stone fragments. A total of 555 fragments varying in number per patient (4-69) and in size (maximum diameters from 0.5-8.0 mm) were recovered by sieving aqueous suspensions of the feces. All 482 fragments less than or equal to 3.0 mm left the biliary tract without any clinical symptoms, as did the three largest fragments with maximum diameters of 7.0-8.0 mm and almost all of the 70 fragments measuring 3.5-5.0 mm. During the observation period, four episodes of biliary complaints were recorded in three patients in whom fragments with maximum diameters of 3.5-5.0 mm were found. The only chemical abnormality was a temporary elevation of lipase activity to twice the normal range in 1 case. All fragments were identified as gallbladder stones by infrared spectroscopy on the basis of their (varyingly high) cholesterol content. By macroscopic criteria, most of the fragments were from mixed stones; therefore, provided there is a functioning gallbladder and sufficiently fine fragmentation, successful extracorporeal shock-wave lithotripsy does not seem to be limited to pure cholesterol stones.