Objectives : It has been known that immune reaction plays an important role in the pathogenesis of otitis media (OM). We investigated the change of middle ear mucosal inflammation induced by lipopolysaccharide (LPS) following administration of Taglisodog-eum (TSE) in experimental animals. Materials and Methods : Otitis media was induced by injecting 1 mg/kg of Pseudomonas aeruginosa LPS transtympanically in 60 rats. These rats were divided into two groups, the LPS group (n=30, remained naive after OM elicitation) and the TSE group (n=30, treated with TSE after OM elicitation) and 6 additional rats were kept as a normal control group (n=6, remained naive until tissue collection). The rats were killed at the 1st, 3rd, and 7th days after challenge. The temporal bones in each group were harvested and examined histopathologically by hematoxyline-eosin stain. Middle ear mucosa were taken at the 1st, 3rd, and 7th days after challenge. The levels of spicing variants of TNF-${alpha}$ transcription were evaluated by Realtime-PCR. Results : TSE suppressed LPS-induced TNF-${alpha}$ mRNA expression and thickness of the submucosal layer and infiltration of inflammatory cells in rat middle ear epithelium. Conclusion : The results suggest that TSE may be effective in decreasing inflammation with particular application to mucosal metaplasia in OM.