A new model of an acute bleeding gastric ulcer with a single bleeding artery in its base has been developed. A suction ulcer defect is created over a large, submucosal artery. Small bleeding marginal vessels are electrocoagulated with a fine-tipped bipolar forceps. The artery in the base of the ulcer is dissected free and then incised longitudinally; brisk bleeding results. A combination of heparin, aspirin, and dipyridamole is used to prevent spontaneous hemostasis. Bleeding from the incised artery of the single vessel ulcer does not decrease over a 10-min interval. No damage to the muscularis externa of the underlying gastric wall results from preparation of the ulcer. The effect of Nd:YAG laser photocoagulation in this new model was compared with the results of photocoagulation in the standard suction ulcer model. In both models the Nd:YAG laser stopped equivalent bleeding from all ulcers. However, there was a marked difference in the depth of tissue injury, with much less damage observed in the single vessel ulcer. This model may provide a better method to assess depth of tissue injury resulting from endoscopic hemostatic techniques.