Inflammatory bowel disease is thought to be regulated by the balance between Th1 and Th2 cytokines secreted by T cells, and NF-κB p65 also plays a predominant role in the intestinal inflammation. We evaluated the potency of oxymatrine, one of active components of Sophora Root, in inhibiting the immune responses and inflammation in 2,4,6-trinitrobenzene sulfonic acid(TNBS)-induced colitis. The inflammation was markedly ameliorated in the oxymatrine-treated rats.The level of IL-2 was increased and that of IL-10 was decreased in colon tissue in the rat model,which was reversed by the treatment of oxymatrine. Moreover, the elevated expression of NF-κB p65in colon tissue in the model was also improved by oxymatrine treatment. Our results suggest that oxymatrine might be beneficial for the abnormal immune responses and inflammation by regulating the unbalance of Th1 and Th2 cytokines secretion and inhibiting the expression of NF-κB p65 in colon tissue.