Idiopathic thrombocytopenic purpura (ITP) is an autoimmune condition in which antibodies react against platelets and cause platelet destruction and bleeding that rarely results in gastrointestinal bleeding. Even though it is still controversial, a recent study suggested that Helicobacter pylori is one of the causes of ITP, and that eradication of H. pylori may be helpful for improving platelet count. We report a case of isolated gastric mucosal hemorrhage not related to H. pylori infection in a patient with ITP. A gastric mucosal biopsy revealed mild lamina proprial edema and extravasated red blood cells but no evidence of vasculitis or inflammatory cell infiltration. Thrombocytopenia can lead to a gastric mucosal hemorrhage not related to an H. pylori infection when treating patients with ITP. (Korean J Gastrointest Endosc 2011;42:241-244)