The morphology of ligated rat stomachs filled with absolute ethanol for 1, 7, 15, 30, and 60 min was studied. With interrupted blood circulation, the entire mucosa was destroyed within minutes. With intact circulation, the mucosae remained macroscopically normal or developed visible lesions. Areas with lesions had extensive surface and gland cell disruption and were hemorrhagic and hyperemic. Histologically, nonlesion sites had about 92% of the mucous cells on the surface and upper gastric pits destroyed within 1 min. Detached necrotic cells and an accumulation of an exudate with fibrin fibers formed a thick layer over the damaged mucosal surface. Intact cells from the gastric pits started migrating over the denuded basal lamina and after 7 min about 4% of the surface was reepithelialized. Within the next 8 min there was a sharp increase in mucosal restitution to about 54%. After 30 min 84% of the mucosa was restituted and there was only a slight increase to about 87% after 1 h of continuous exposure to ethanol. After 30 min the ethanol was diluted to about 40% vol/vol. Focal geyserlike eruptions of plasma containing polymerized fibrin were visible at sites of epithelial discontinuity. Restitution of the mucosal surface in the presence of luminal ethanol may be facilitated by the favorable microenvironment created by the thick unstirred layer formed by the mucoid coat of necrotic cells, fibrin, and continued plasma shedding.