Schizandra chinensis fruits (SC) have been used as a traditional Oriental medicine for treatments of many stress-induced diseases. In the present study, we investigated the protective effect of SC aqueous extract(SC-Ex) in the inflammatory diseases of intestine using a mouse model of ulcerative colitis. An experimental colitis was induced by daily treatment with 5% dextran sulfate sodium (DSS). SC-Ex was orally administered from day 2 of DSS treatment in a dose-dependent manner. Administration of SC-Ex reduced significantly clinic signs of DSS-induced colitis, including body weight loss, shorten colon length, increased disease activity index, and histological colon injury. Moreover, SC-Ex suppressed significantly not only the activities of myeloperoxidase (MPO) and chymase, but also the expressions of $TNF-{acute{a}}$ and COX-2 in DSS-treated colon tissues. Inhibitory effect of SC-Ex was effective at a dose over 20 mg/kg. Our results indicate that SC-Ex may possess therapeutic effect on the development of DSS-induced colitis.