We evaluated the effect of sucralfate in patients with early gastric cancer in endoscopic mucosal resection (EMR)-induced gastric ulcers, and in rats with acetic acid-induced ulcers, by measuring concentrations of aluminium adhering to mucosal lesions. Twenty-two patients who underwent EMR received sucralfate with or without ranitidine and were examined endoscopically after 1 week, 2 weeks and 3 weeks. Gastric juice pH and concentration of aluminium in samples of ulcerated and normal mucosa were measured at various time-points. Good ulcer healing was observed in all patients. Significantly higher concentrations of aluminium were found in ulcerated tissue compared with normal mucosa. This selective binding of sucralfate was even found 12 h after drug administration and was confirmed in acetic acid-induced ulcers in 40 rats. Neutral rather than acid gastric juice was observed up to 12 h after the administration of sucralfate alone. These results suggest that sucralfate with or without ranitidine may contribute to the healing of EMR-induced ulcers by selectively binding to lesions.