We report a case of choledochocele associated with choledocholithiasis. The patient became symptomatic when a gallstone was trapped within the choledochocele, causing intermittent biliary obstruction. Endoscopic retrograde cholangiography (ERC) provided the diagnosis and endoscopic sphincterotomy was performed for definite non-operative treatment. The lesion could not be identified on ultrasound even after its demonstration by ERC. The importance of direct cholangiography in the diagnosis of a choledochocele is discussed.