Dogs with a vagally denervated (Heidenhain) pouch and a gastric fistula were used to investigate the humoral mechanism which would affect the gastric acid secretion following acute intragastric ethanol administration. Ethanol solutions induced a doserelated secretion of gastric acid. Although plasma gastrin levels increased after the loading of both 20% and 30% ethanol solutions, there was a discrepancy between total acid output and the integrated gastrin response. Plasma secretin levels also augmented after the administration of ethanol solutions, with a delay of about one hour after the onset of acid secretion. The response of gastric inhibitory polypeptide (GIP) to ethanol was very slight, similar to that of insulin. There was a significant rise in plasma glucose levels after the instillation of 30% ethanol solution as in the case of liquid meal. It is concluded that gastrin may be merely one of the factors which stimulate acid secretion after ethanol administration, and that gastric acid would have a close relationship with secretin release. It is also probable that acid is not an effecitve stimulant to the release of GIP.intragastric ethanol administration ; gastric acid secretion ; gastrin ; secretin ; GIP Since 1898 (Chittenden et al. ), many investigators have reported the relationship between alcohol intake and gastric acid secretion. However, their results did not always agree. Some persons showed the stimulatory effect of alcohol on gastric acid secretion (Hirschowitz et al. 1956;Woodward et al. 1957;Lenz et al. 1983), others reported the opposite (Cooke 1972;Kuo and Shanbour 1983). Regarding the mechanism by which alcohol affects acid secretion, many factors (such as species differences, route of administration, etc.) have been pointed out by those researchers. Moreover, as remarkable advances in the study of gastrointestinal hormones have been made, some hormones (e.g. gastrin and secretin) have been referred to as substances which mediate the action of alcohol on gastric acid