AIM: Endoscopic sphincterotomy (ES) is a well-established therapeutic modality for the removal of common bile duct (CBD) stones. After ES there are still around 10% of patients that experience recurrent CBD stones. The aim of this study is to investigate the composition of CBD stones before and after ES and its clinical significance in Chinese patients.METHODS: From January 1996 to December 2003, 735Veterans General Hospital and stone specimens from 266patients were sent for analysis. Seventy-five patients had recurrent CBD stones and stone specimens from 44patients were sent for analysis. The composition of the stones was analyzed by infrared (IR) spectrometry and they were classified as cholesterol or bilirubinate stones according to the predominant composition. Clinical data were analyzed.RESULTS: In the initial 266 stone samples, 217 (82%)were bilirubinate stones, 42 (16%) were cholesterol stones,3 were calcium carbonate stones, 4 were mixed cholesterol and bilirubinate stones. Patients with bilirubinate stones were significantly older than patients with cholesterol stones (66±13 years vs 56±17 years, P= 0.001). In the 44 recurrent stone samples, 38 (86%) were bilirubinate stones, 3 (7%) were cholesterol stones, and 3 were mixed cholesterol and bilirubinate stones. In 27 patients, bothinitial and recurrent stone specimens can be obtained,23 patients had bilirubinate stones initially and 2 became cholesterol stones in the recurrent attack. In the four patients with initial cholesterol stones, three patients had bilirubinate stones and one patient had a cholesterol stone in the recurrent attack.CONCLUSION: Bilirubinate stone is the predominant composition of initial or recurrent CBD stone in Chinese patients. The composition of CBD stones may be different from initial stones after ES.