The effect of milk or calcium in the prevention and treatment of ethanol-induced gastric mucosal damage in rats was examined. Thirty per cent ethanol induced gastric lesions and increased the gastric luminal calcium content. Milk pretreatment reduced ethanol-induced mucosal damage. Calcium administered at a concentration equivalent to that found in milk (1.28 mg ml-1) and ten times higher (12.8 mg ml-1) produced similar protective effect in a dose dependent manner. No protective action was observed in rats pretreated with protein (casein) or phosphate buffer solution, which are of the same concentration or buffering capacity as found in the milk sample, respectively. Rats with ethanol-induced gastric lesions healed more quickly when they were treated with milk or calcium (at 1.28 and 12.8 mg ml-1 respectively). The concentration of calcium employed in this study did not stimulate acid secretion. It is concluded that milk could be beneficial to the healing of gastric mucosal lesions and this may be due to the membrane stabilization and to cellular restitution by calcium in milk.