Abstract: Pyrrole aldehydephenyl semicarbazone was shown to be an effctive anti-ulcer agent in five experimental models in rats, namely, the indomethacin-induced, acetic acid-induced, pyloric ligation-induced and 0.6 mol HCl, absolute alcohol-induced ulcers, at doses of 40～100 mg/kg. Its anti-ulcer activity and characteristics are similar to those of furazolidone. Its oral acute toxicity in mouse is much lower than furazolidone. This compound exhibited mild inhibitory effects on gastric pepsin secretion, caused increases in hexosamine level and decreases of DNA content in gastric juice. It showed no influence on gastric acid secretion and was considered to tare "cytoprotective action" on the gastric mucosa. However, this compound was found to be ineffective against the stress-restraint gastric ulcer model.