Objectives: This study was carried out to investigate the protective effect of Coptidis Rhizoma steamed with rice wine (CR) against gastroduodenal mucosal injury through inhibiting inducible nitric oxide synthase (iNOS) activation. Methods: In in vitro experiment, LPS-induced RAW 264.7 macrophages were treated with CR(0.4, 0.6, 0.8, 1.0 mg/ml) and iNOS mRNA expression and nitric oxide (NO) production were measured. In in vivo experiment normal group mice were treated with neither ethanol nor CR. Both control and sample group mice were orally administrated with ethanol. Five hours after ethanol administration control group mice were orally administrated with distilled water, sample group mice were orally administrated with CR. After three days administration, gastroduodenal mucosa of mice was observed histopathologically and iNOS, nuclear factor-kappa B (NF-${kappa}B$) activation were observed immunohistochemically. Results: In in vitro experiment iNOS mRNA expression and NO production in LPS-induced RAW 264.7 macrophages were decreased by CR dose-dependently. In in vivo experiment, gastroduodenal mucosal injury was repaired by CR and iNOS, NF-${kappa}B$ activation in gastroduodenal mucosa were decreased by CR. Conclusions: Coptidis Rhizoma steamed with rice wine has a protective effect against gastroduodenal mucosal injury through inhibiting iNOS activation.