Background/Aims: To understand the epidemiologic characteristics of gallstone disease in Korea and to evaluate the chronological changes of gallstone disease, the authors performed this prospective nationwide cooperative study. Methods: The subjects were 1,263 patients with gallstone. They were hospitalized at 19 hospitals in Korea from February to July, 1997. The study protocols were recorded on 1,263 patients and gallstones were removed from 1,133 patients and their chemical compositions were analyzed. Results: Among total patients with gallstone, the proportions of patients with gallbladder, common bile duct(CBD) and intrahepatic duct(IHD) stones were 64.0%, 21.9%, and 14.1%, respectively. Male to female ratio was 1 versus 1.3. The gallbladder stones were categorized as cholesterol (58.1%), black pigment (25.2%) and brown pigment (12.1%) stones. The CBD stones were classified into brown pigment (76.1%), cholesterol (18.4%) and black pigment (3.5%) stones. The IHD stones were classified into brown pigment (61.4%) and mixed (35.6%) stones. The mean cholesterol contents of intrahepatic mixed stones were 63.4±20.8%. Obesity was the risk factor in patients with cholesterol gallstones. Conclusions: This study showed that the type and composition of gallstones in Korean patients might be changing when these results were compared with previous reports. The repeat of nationwide cooperative epidemiologic study may be necessary to elucidate the changing pattern of gallstone disease confirmatively.