Objectives : The aim of the current study was to investigate the effects of Sargassum (Sargassum pallidum (TURN.) C. AG.; SP) on the experimental colitis induced by 2,4,6-trinitrobenzene sulfonic acid (TNBS) in mice. Methods : ICR mice were divided into 7 groups (NOR, CON, $SS50 imes5$, $SP20 imes3$, $SP50 imes3$, $SP20 imes5$, $SP50 imes5$). TNBS processing was intrarectally applied to all experimental groups on the 3rd experiment day, except the normal group (NOR). For investigating the prophylactic effect, SP at doses of 20 mg/kg ($SP20 imes5$) and 50 mg/kg ($SP50 imes5$) were orally administered for 5 days. The SP at doses of 20 mg/kg ($SP20 imes3$) and 50 mg/kg ($SP50 imes3$) were orally administered for 3 days after the colitis induction in order to check the effect of treatment. As a positive control group, sulfasalazine 50 mg/kg ($SS50 imes5$) was administrated. Macroscopic findings of epithelial tissue on mice were measured by colon length and macroscopic score. Histologic findings were also checked by crypt cell, epithelial cell, inflammatory cell and edema of submucosa. We measured the ability of SP to inhibit lipid peroxidation and myeloperoxidase activity. We also measured levels of the inflammatory markers, interleukin (IL)-$1eta$ and cyclooxygenase-2 (COX-2), its transcription factor activation, phospho-NF-${kappa}B$ (pp65), in the colon by enzyme-linked immunosorbent assay and immunoblot analysis. We measured activation of fecal bacterial enzyme, $eta$-glucuronidase and degradation activation of fecal glycosaminoglycan (GAG), and hyaluronic acid. Results : Oral administration of SP on mice inhibited TNBS-induced colon shortening and myeloperoxidase activity in the colon of mice as well as IL-$1eta$ and COX-2 expression. SP also inhibited TNBS-induced lipid peroxidation and pp65 activation in the colon of mice. SP inhibited $eta$-glucuronidase activation and fecal hyaluronic acid degradation activation as well. Conclusions : SP could be a possible herbal candidate and preventive prebiotic agent for treating inflammatory bowel disease (IBD). Further experiments to differentiate effects of SP on IBD, such as other solutions and extracting times, might be promising.