The author studies the effect of 0.25 I.U./kg. body wt. of insulin by intravenous route on gastric secretion stimulated by intravenous histamine administered at a dose of 0.02 mg./kg. body wt./hr. in 21 patients without digestive disease. He found that insulin increases the already stimulated gastric secretion and did not find the inhibition reported by others. Simultaneously, the author reviews the literature with the finding of the mentioned inhibitory and stimulant action of insulin and lists the possible causes of this paradoxical effect.