The anti-H.pyloriactivity ofPterocarpus santalinus(PS), a traditional herb, has been assessed and compared with that of bismuth subcitrate, throughin vitrostudies employing rat gastric epithelial cell cultures andH. pyloriisolates from gastric mucosal biopsy patients. The MIC of PS was found to be 20 μg/mL.H. pyloriwas co-cultivated with rat gastric epithelial cells in the presence/absence of PS at its MIC. A reduction in the activity of urease, a normal appearance of the epithelial cells on electron microscopic examination,a decrease in lipid peroxidation and lactate dehydrogenase suggests the possible anti-H.pyloriactivity of PS. Copyright © 2006 John Wiley & Sons, Ltd.