Extracorporeal shock wave lithotripsy (ESWL), generated by the Siemens lithotripter (Lithostar), was used in six patients (two males, four females, aged 28 to 70 years) with large bile duct stones (diameter 16 mm to 30 mm; single in five, multiple in one) in whom routine endoscopic measures had failed. Disintegration of stones was achieved in four patients. The mean number of shocks delivered per patient, at energy levels generated by 19 kv, was 18,267 (range 4200-39,000) over 1 to 8 sessions, with a maximum of 6000 shocks per session. Exacerbation of cholangitis occurred in one patient after stone disintegration. Cutaneous petechiae were noted in four patients. Our report describes the use of a very high number of shock waves in the treatment of bile duct stones, with no appreciable short term complications noted in this small experience. Our initial experience of treating large bile duct stones with ESWL appears encouraging and safe.