Objective: To investigate the effects of different biliary drainage methods on gastric mucosa in rats with obstructive jaundice (OJ) and the mechanisms. Methods: Eighty SD rats were randomized into sham operation group, OJ model group (model group), OJ model plus internal biliary drainage group (internal drainage group), and OJ model plus external biliary drainage group (external drainage group), and the total experiment time was two weeks. At the end of the experiment, rats in each group were sacrificed and the histological changes in gastric mucosa were observed; the serum endotoxin and endothelin 1 (ET-1) levels, and ET-1 level and endothelin receptor type A (ET-A) mRNA expression in gastric mucosal tissues were determined. Results: All rats, except those in sham operation group, showed gastric mucosal injury of varied severity, but the injury in internal drainage group was remarkably milder than that in either model group or external drainage group. Compared with sham operation group, the serum endotoxin and ET-1 levels, and ET-1 and ET-A mRNA expression levels in gastric mucosal tissues in both internal drainage group and external drainage group were markedly increased, and all differences reached statistical significance (all P<0.05), while they were slightly increased in internal drainage group, but with no statistical differences (all P>0.05). Conclusion: Internal biliary drainage exerts protective effect on gastric mucosa in OJ rats, and the mechanism is probably due to its reducing ET-1 level and ET-A expression.