Secondary duct stones are usually detected and easily removed at the time of cholecystectomy either during surgery or endoscopically before or after the operation. Primary duct stone diseases, although much less common, are often a greater therapeutic challenge. These stones may be huge, distributed throughout the biliary tree (including areas difficult to access), and unresponsive to pharmacologic measures. Recurrence of primary duct stones is the rule rather than the exception, and reliable methods for prevention remain to be established. Moreover, morbidity and mortality due to biliary obstruction, sepsis, and choliangiocarcinoma make primary bile duct stone disease a formidable adversary. A better understanding of their pathogenesis can facilitate more effective approaches to treatment and, most important, prevention.