The action of intragastric ethanol in various concentrations (1.4%-40% vol/vol) and of beer, white wine, cognac, and whisky on gastric acid secretion and release of gastrin was studied in healthy humans. Ethanol concentrations of 1.4% and 4% (vol/vol), but not higher, significantly (p less than 0.05) increased gastric acid secretion to 23% and 22%, respectively, of incremental maximal acid output [i.e., observed response to pentagastrin (6 micrograms/kg s.c.) minus basal acid output]. The 1-h incremental gastric acid responses to beer and wine were 96% and 61%, respectively, of incremental maximal acid output. Neither cognac nor whisky had any stimulatory effect. The 1-h incremental gastric acid response to an 8% peptone meal was 40% of incremental maximal acid output, and to peptone plus white wine 77%. Plasma gastrin levels were not altered by ethanol, cognac, and whisky. The 1-h integrated plasma gastrin responses to beer and white wine were 119% and 77%, respectively, of the response to the peptone meal. We conclude that (a) the action of pure ethanol on gastric acid secretion is related to its concentration: concentrations of 1.4% and 4% are moderate stimulants; concentrations of 5%-40% have no effect, or rather an inhibitory effect; (b) beer and white wine, but not whisky and cognac, are potent stimulants of gastric acid secretion; (c) the stimulatory mechanism of low ethanol concentrations is unknown; and (d) nonalcoholic constituents of beer and wine are most likely responsible for the stimulatory actions of both beverages on gastric acid secretion and release of gastrin.