To determine its usefulness and the factors affecting the fragmentation rate of extracorporal shock-wave lithotripsy (ESWL) in bile duct stones, we analyzed the results of 22 patients with CBD and/or IHD stones (total number of target; 30 targets) who performed the ESWL using the electromagnetically generated lithotriptor, Lithostar (Siemens) from June 1988 to September 1990. 1) Among the 30 targets, 22 targets (73.3%) achieved the disintegration of stones, and the fragmented stones were removed by spontaneous passage or extraction using Dormia basket or balloon. 2) Comparing the fragmentation rate according to the location, number, size and shape of the stones, the more successful rate was obtained in CBD stones than IHD stones (88.9% VS. 50.0%), in single stones than in multiple stones (94.1% vs 46.2%), in stones less than 2cm than in those larger than 2cm (86.7% vs. 60.%), and in round or rectangular shaped than in irregular contoured stones (89. 5% vs 75.0 % vs 28.6 %).3) Comparing the success rate according to location by number of stones, the fragmentation rate of single stones located in CBD and IHD was 92.9% and 100% and multiple stones 75.0% and 33.3% respectively. According to location by size, the success rate in stones less than 2cm located in CBD and IHD was 83.3% and 100%, respectively and in stones more than 2cm 100% and 33.3% respectively. According to location by shape, the fragmentation rate in round stones located in CBD and IHD was 92.9% and 100%, respectively, in rectangular stones of CBD 75.0% and in irregular stones of IHD 28.6%. 4) Apart from mild fleabite-like petechiae and pain at the site of shock-wave transmission, transient elevation of serum amylase and hemobilia which normalized after 48 hours, no other serious side effects were observed. In our experiences, we conclude that extracorporeal shock wave lithotripsy was a safe, easily applied, useful method for the treatment of bile duct stones not amenable remaval by conventional measures.