To clarify the role of endotoxaemia and congestion of the stomach in the development of acute haemorrhagic gastritis in cirrhotic patients and to investigate the mechanisms of gastric mucosal haemorrhage, the present study was undertaken using rats. Congestion of the stomach was produced by the ligation of gastric veins. Congestion of the stomach or endotoxaemia could not produce gastric mucosal haemorrhage by itself. However, petechial haemorrhage was induced when endotoxin was given to the rats with congestion of the stomach, and the gastric mucosal haemorrhage was largely prevented by administration of gabexate mesilate, an anti-kallikrein drug. Administration of bromelain, which releases prekallikrein and high molecular weight kininogen, instead of endotoxin, also induced gastric mucosal haemorrhage. These findings suggest that the cause of acute haemorrhagic gastritis may be the coexistence of endotoxaemia and congestion of the stomach due to liver cirrhosis and portal hypertension. The mechanisms of the haemorrhage may be as follows: Endotoxin-induced bradykinin acts on the dilated capillaries and small veins in the mucosa and markedly increases their permeability.