Cellobiose is produced from cellulose using specific bacterial enzymes, and is hydrolyzed into glucose by the enzymes cellobiosidase and cellulase. In this study, we examined the effects of cellobiose on colonic mucosal damage in a dextran sulfate sodium (DSS) colitis model. BALB/c mice were divided into two groups. In the first group, the mice were fed 3.5% DSS mixed with normal chow. In the second group, the mice were fed 3.5% DSS plus 6.0 or 9.0%(weight/weight) cellobiose mixed with normal chow. The development of colitis was assessed on day 21. Mucosal cytokine expression was analyzed by RT-PCR. Body weight loss was significantly attenuated in the 9.0% cellobiose-fed DSS mice as compared to the DSS mice. Colonic weight/length ratio, a maker of tissue edema, was significantly higher in the DSS mice than in the 9.0% cellobiose-fed DSS mice. The disease activity index and histological colitis score were also significantly higher in the DSS mice than in the 9.0% cellobiose-fed DSS mice. Mucosal mRNA expression for IL-1β, TNF-α, IL-17 and IP-10 were markedly reduced in the 9.0% cellobiose-fed DSS mice. In conclusion, a preventive effect of cellobiose against DSS colitis suggests its clinical use for inflammatory bowel diseases patients.