Gastric cold irrigation is widely used in the treatment of gastric bleeding. The purpose of this study was that of studying the effect of cooling on gastric mucosal lesions induced by hemorrhagic shock. The gastric transmucosal potential difference (GTPD) and the severity of ulceration were assessed in rats subjected to continuous gastric irrigation with 0.1 N HCl at a temperature of 37 or 5 degrees C. The effect of gastric cooling was evaluated in basal conditions and in rats subjected to hemorrhagic shock. Although gastric cooling has been able to cause ulcers in basal conditions, it showed a protective effect during hemorrhagic shock, reducing the degree of ulceration and improving the GTPD recovery. It is likely that the decrease in cellular metabolic requirements induced by cooling plays an important role in mucosal protection during hemorrhagic shock.