HH01(1-methyl-3,4,5,6,9,10-hexahydro-7H-cyclopenta [j,k]-1,3-dioxolo [4,5-h]-pyrrolo[2,1-b] [3]-benzazepine) A and B in doses 30 mg.kg-1 and 60 mg.kg-1 were shown to protect gastric mucosa of rats from damage induced by absolute ethanol, cold-immersion stress and pylorus ligation. No effect was found in indomethacin model in mice. HH01 was found to decrease secretion of gastric juice and HCl in pylorus ligated rats. The content of DNA in gastric juice of animals treated with HH01 was lower than in control. The results suggest that HH01 is effective as an anti-ulcer agent, but its mechanism of action is yet unknown.