Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the colon and rectum with intervals of acute exacerbation. Its etiology remains unknown, although recent studies suggest that pro-inflammatory cytokines initiate the inflammatory responses. In this study, we investigated the ameliorative effects of YB-21 (new product containining Lactobacillus plantarum, Barley Bran and Nymphaeaceae) in a dextran sulfate sodium (DSS)-induced colitis in mice. The experimental groups were divided into 6 groups (n = 10) of ICR mice: normal control(NC), DSS-treated(PC, positive control), DSS+latic-L-treated (3×107CFU/ml), DSS+latic-M-treated (3×109CFU/ml), DSS+latic-H-treated (3×1011CFU/ml), and DSS+YB-21-treated. Histological examinations indicated that YB-21 suppressed edema, mucosal damage, and the loss of crypts induced by DSS. Moreover, YB-21 reduced serum level expressions of, tumor necrosis factor-α (TNF-α). These results suggest that YB-21 has an anti-colitic effect by the suppression of intestinal inflammatory responses in DSS-induced colitis in mice.