This retrospective, observational study was designed to analyse recent trends in the age distribution of westernized persons in South Korea with common bile duct stones (cholesterol, brown and black stones). Data on 253 patients who had received endoscopic surgery at a tertiary referral hospital in Daegu, the third largest South Korean city, were used to investigate the relationship between the numbers of patients with different types of common bile duct stones and age. There were strong correlations between age and the frequency of the three different types of common bile duct stones. The frequency of cholesterol stones decreased exponentially with increasing patient age, whereas the frequency of brown stones increased exponentially. Patients with black stones showed a Gaussian-like age distribution. Thus, the age-dependency of the frequency of these three common types of bile duct stones differed from one another within this patient population.