Twenty-six patients with liver neoplasm receiving transcatheter arterial chemoembolization (TAE) therapy underwent gastroduodenal endoscopic examinations before and after TAE. The balloon was inflated in the common hepatic artery before chemoembolization if superselective cannulation beyond the gastroduodenal artery could not be done. Sixteen of the 26 patients (61.5%) showed new gastroduodenal lesions, with superficial gastritis in six, one or more erosions in nine, and hemorrhagic gastritis in five. The frequency of lesions detected was no different when the common hepatic artery was obstructed (60.0%) than when superselective embolization was done in more peripheral branch(es) (60.0%). No clinical events indicating upper gastrointestinal bleeding were noticed after TAE. The presence of esophageal and/or gastric varices and session(s) of TAE performed before did not affect the occurrence of gastroduodenal lesion(s). We conclude that TAE produces erosive gastroduodenal lesions that are detected by endoscopic examination but are clinically unimportant; balloon catheter occlusion of the common hepatic artery did not result in more frequent gastroduodenal complications than the ordinary superselective chemoembolization method.