AIM: To investigate the role of NF-κB in the pathogenesis of TNBS-induced colitis in rats.METHODS: Thirty-two healthy adult Sprague-Dawley (SD)rats were randomly divided into four groups of eight each:normal, NS, model I, model Ⅱ groups in our study. Rat colitis model was established through 2-,4-,6-trinitrobenzene sulfonic acid (TNBS) enema. At the end of four weeks,the macroscopical and histological changes of the colon were examined and mucosa myeloperoxidase (MPO)activities assayed. NF-κB p65 expression was determined by Western blot assessment in cytoplasmic and nuclear extracts of colon tissue, and the expressions of TNF-αand ICAM-1 protein in colon tissue were examined by immunohistochemistry. The relativities between expression of NF-κBp65 and other parameters were analyzed.RESULTS: TNBS enema resulted in pronounced pathological changes of colonic mucosa in model Ⅱ group (macroscopic and histological injury indices 6.25±1.39 and 6.24±1.04,respectively), which were in accordance with the significantly elevated MPO activity (1.69±0.11). And the nuclear level of NF-κB and expression of TNF-α, ICAM-1 in rats of model Ⅱ group were higher than that of normal control (9.7±1.96 vs1.7±0.15, 84.09±14.52 vs16.03±6.21,77.69±8.09 vs13.41±4.91 P＜0.01), Linear correlation analysis revealed that there were strong correlations between the nuclear level of NF-κB and the tissue positive expression of TNF-α and ICAM-1, MPO activities,macroscopical and histological indices in TNBS-induced colitis, respectively (r = 0.8235, 0.8780, 0.8572, 0.9152,0.8247; P＜0.05).CONCLUSION: NF-κB plays a pivotal role in the pathogenesis of ulcerative colitis, which might account for the up-regulation the expression of TNF-α and ICAM-1.