Ulcerative colitis, one of the most important inflammatory bowel diseases, affects millions of people worldwide. The aim of this study was to investigate the effects of Saikosaponin A on dextran sulfate sodium (DSS)-induced colitis in mice. The mice were treated with 2.5% DSS for 5 d to induce acute colitis. Saikosaponin A was given 3 d before and during DSS treatment by intragastric administration. The results showed that Saikosaponin A significantly inhibited DSS-induced body weight loss and shortening of colon length. DSS-induced colonic histological changes and MPO activity were also prevented by treatment of Saikosaponin A. The levels of TNF-α and IL-1ß were increased by DSS and dose-dependently inhibited by Saikosaponin A. Furthermore, Saikosaponin A significantly inhibited DSS-induced NF-κB activation and up-regulated the expression of LXRα. Taken together, our results indicated that Saikosaponin A had protective effects against DSS-induced colitis. Saikosaponin A protected DSS-induced colitis through inhibiting inflammatory response.