The definition of large stones is not clear ranging from 10 mm to 15 mm and does not include the lower common bile duct (CBD) diameter. Three hundred and four patients who underwent endoscopic retrograde cholangiopancreatography and stone extraction were retrospectively analyzed over a 1-year period. Sixteen patients were different from others in that 10 patients with large stones had stone extraction with a wire basket or a balloon catheter and 6 patients with small stones had stone extraction with mechanical lithotripsy. The definition of large stones should include diameter of the lower CBD and any stone in lower CBD with its diameter greater than 2 mm.