Agenesis of the gallbladder, which is an extremely rare anomaly, may present with biliary symptoms but is virtually impossible to diagnose by such conventional investigations as oral cholecystogram or ultrasonography. We report herein a case of a young man presenting with episodic epigastric pain on whom an ultrasonographic diagnosis of gallstones was made. A gallbladder was not visualized on oral cholecystogram, however, he was subsequently found to have agenesis of the gallbladder, the diagnosis of which was confirmed by intra-operative cholangiography and a postoperative N-2,6-dimethylphenylcarbamoyle methyl iminodiacetic acid scan (HIDA scan). His symptoms responded to antiulcer treatment with upper gastrointestinal endoscopic findings suggestive of oesophagitis and duodenitis.