Experiments on dogs with Basov's gastric fistulas were made to study the effect of amino acids with branched carbon chains (L-isoleucine, L-leucine, L-valine) on gastric secretion. The mixture of amino acids in a concentration of 0.16 M exerts a powerful enough stimulant action, provoking gastric secretion amounting to 2/3 of the value obtained during sham meat feeding. The value of the secretion determined by other amino acids (L-alanine, L-proline) was the same. Unlikely, gastric secretion provoked by glycine (0.16 M) was approximately 1.5 times more intense as compared to that induced by the mixture of amino acids with branched carbon chains. The intense action of glycine is likely to be related to the fact that, apart from the properties common to other amino acids, it possesses the properties of neurotransmitters. L-glutamic acid (0.1 M) administered to the blood produces marked inhibition of gastric secretion caused by the mixture of amino acids with branched carbon chains and the same inhibition of secretion due to administration of other amino acids.