The antiulcerogenic activity of Dalbergia monetaria L. (Leguminosae-Fabaceae) lyophilized aqueous extract (LAE) was studied in four models of gastric ulcers in rats, LAE showed a dose dependent inhibition of gastric lesions induced by indomethacin, ethanol, pylorous ligature and hypothermic-restraint stress. LAE extract was more effective against hypothermic-restraint stress-induced lesions and less effective against indomethacin-induced gastric mucosal damage, The effectiveness on the ethanol and pylorus ligature induced gastric lesions was equivalent, On the other hand, LAE did not modify mucus secretion in gastric lesions induced by stress, The oral administration of LAE did not produce any toxicity signals until 5 g/kg, Proanthocyanidins present in this species are phenolic compounds that inhibit the histidine decarboxylase enzyme, Thus, the mechanism involved in the reduction of ulcerative lesions of rat gastric mucosa produced by the LAE of D. monetaria may be related to its property of inhibiting histamine production. (C) 1997 by John Wiley & Sons, Ltd.114314316