To investigate the effect of bile acid on gastric mucosa, we performed biologic test using Sprague-Dawley rat. Mixture solution of TDCA 15mM and Hcl of pH 3 was given into stomach to one group and HCl of pH 3 was given into stomach to another group. The significant gastric mucosal change was vasodilation and edema, that was disappeared progressively. These findings suggest the bile acid and damage gastric mucosa.