Under many operational situations, military personnel are unable adequately to increase heat production by muscle activity in response to cold stress. An agent capable of increasing visceral heat production might be useful in the prevention of cold injury. Glycine, an amino acid with a high specific dynamic action, was given in 30 gm. oral doses to six young adult males. The individuals served as their own controls when receiving 30 gm. glucose. In a 29° C. room 1 hour after ingestion, glycine produced an average 9.2% increase in resting metabolism. In a -17.8° C. (0° F.) cold room 2 hours after ingestion of glycine, metabolism continued higher and the subject had higher toe, forehead, and average body temperatures. No differences were noted in finger temperatures, but forefinger blood flow was greater when glycine was ingested. Glycine may be of practical value in increasing heat production under certain conditions.