The effect of Ginseng total saponin on the absorption of nalidixic acid in small intestine of rats was investigated. Circulation apparatus designed by Wiseman and Symth was employed with minor modification. In this apparatus, pH 7.4 Krebs bicarbonate buffer solution containing 20㎍/㎖ nalidixic acid was used as the inner solution (mucosal side) and pH 7.4 Krebs bicarbonate buffer without nalidixic acid was used as the outer solution(serosal side). The Ginseng total saponin was added into the mucosal side to be 0.01%, 0.03% and 0.06% in concentration, respectively. The results obtained will be summarized as follows; 1. Ginseng total saponin increased the in vitro absorption of nalidixic acid in small intestine significantly (p<0.001). 2. Ginseng total saponin did not affect the solubility of nalidixic acid siginificantly. 3. Ginseng total saponin increased partition coefficient of nalidixic acid significantly (p<0.001) between buffer (pH 7.4) and chloroform. 4. Therefore, it seemed that the increase in absorption might be due to the increase of lipophilicity of nalidixic acid in the presence of Ginseng total saponin.