Helicobacter pylori specifically adheres to host cells, mainly based on carbohydrate-mediated cell-cell interactions. Previously, we investigated the anti-adhesive effect of polysaccharide fractions from Artemisia capillaris and Panax ginseng, using hemagglutination and enzyme-linked glycosorbent assays. In the present study, each active polysaccharide fraction was further purified, resulting in a single peak (fraction F2) using gel filtration FPLC, in which no protein content was detectable. Using scanning electron microscopy, we examined the inhibitory effects of these polysaccharides on the attachment of H. pylori to the human gastric adenocarcinoma epithelial cell line. The bacterial attachment to the cell line was inhibited by these polysaccharides in the range of the concentrations studied (0.2 - 2.8 mg/mL), showing their minimum inhibitory concentration at as low as 0.2 mg/mL. The bacterial binding was inhibited more effectively by P. ginseng polysaccharides, than by those from A. capillaris. The purified polysaccharides contain similar sugar compositions and have high amounts of uronic acids. Our results suggest that acidic carbohydrates may play an important role in the inhibitory activity on H. pylori adhesion to host cells and that our established purification protocol can be applied to obtain active acidic polysaccharides from plant sources.