Background/Aims: The association between periampullary diverticula and biliary calculi has been reported, but the results are different according to the anatomical location of the stones. The aim o this study was to investigate the association between periampullary diverticula and the incidence of gallstones according to the location of gallstones and the type of diverticula. Methods: For the seven hundred ninety five cases, the results of endoscopic retrograde cholangiopancreatography (ERCP) were analysed. The gallstones were classified into choledocholithiasis, cholecystolithiasis and combined case according to their locations. Incidence of gallstones was determined according to the type o periampullary diverticula. Results: The prevalance of biliary calculi was higher in patients with periampullary diverticula than in patients without it (p<0.001). Considering the locations of gallstones choledocholithiasis was observed in 49.2% of patients with periampullary diverticula and in 28.0% of patients without it (p<0.003). There was no statistical correlation between the type of periampul lary diverticula and the incidence of gallstones (p>0.05). Conclusions: This study shows that there is a significant association between periampullary diverticula and primary choledocholithiasis and no correlation between the type of periampullary diverticula and the incidence of gallstones. (Kor J Gastroenterol 1999;33:252 - 257)