In order to clarify the pathogenesis of gastric mucosal lesions in patients with liver cirrhosis(LC), gastric mucosal blood flow(BF), potential difference(PD) and prostaglandin E(2)(PGE(2)) of patients with LC were analyzed. Of 277 patients with LC, gastric ulcer or gastric erosions were observed in 178 patients (64.2%). The incidence of gastric mucosal lesions in patients with LC correlated with the degree of liver damage estmated by Child's classification. BF, PD and PGE(2) in patients with LC were lower than in control patients without liver disease. BF and PD decreased as the liver damage progressed. These results support the view that the impairment of the defensive factors of gastric mucosa represented by BF and PD play an important role in the pathogenesis of gastric mucosal lesions in patients with LC. PGE(2) was also implicated to be related to the pathogenesis of such lesions.