Nitro-glycerin-in-beeswax is shown to aid and abet the histamine produced ulcer in dogs and rabbits. The effect of nitroglycerin is believed to be due to its venous pooling property; and this action coupled with normal arteriolar reflex contractile responses, leads, after prolonged admn. to resultant areas of impaired circulation in the mucous membrane of the esophagus, stomach and duodenum. These areas of lowered resistance are then subjected to acid-peptic digestion with resultant ulcer and/or erosion formation.