We investigated the quantitative changes in colonic mucins of rats with colitis. Male Wistar rats were treated with dextran sodium sulfate (DSS) or N-ethylmaleimide (NEM) to induce colitis. Both DSS and NEM caused depletion of goblet cells, infiltration of inflammatory cells and erosion at the colonic mucosa around the anus. Though the goblet cells decreased, colonic mucins increased in the distal colon. These phenomena may explain the clinical features of human ulcerative colitis, namely the goblet cell depletion and the mucous stool. The increase of colonic mucins may be a compensatory function of the colon tissue in response to the localized decrease of mucin production.