This study investigated the anti-inflammatory activity of ethanol extracts of Hericium erinaceus in the inflammatory bowel disease (IBD) model. Twenty C57BL/6 mice were exposed to 2% (w/v) dextran sulfate sodium (DSS) in their drinking water for 7 d to induce acute intestinal inflammation. Orally administrated ethanol extract of H. erinaceus (HEEE) (250 mg/kg/d and 500 mg/kg/d body weight) could significantly (P < 0.05) improve body weight and colon length and decreased the intestinal bleeding of DSS-treated mice compared with DSS-treated mice not given HEEE. HEEE markedly reduced DSS-induced myeloperoxidase accumulation in colon tissues, attenuated histological change in the neutrophils and lymphocyte infiltration, and protected the mucosal epithelium. Mechanistically, HEEE ameliorated colitis not only by suppressing the production of inflammatory mediators including tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 in colon tissues but also by adjusting the production of nitric oxide, malondialdehyde, and superoxide dismutase in serum to suppress the oxidative stress. These results suggest that HEEE can be applied as a protective agent in the treatment of IBDs.