This study was designed to investigate the anti-inflammatory activity of the pure compound gentiopicroside (Gent) on dextran sulfate sodium (DSS)-induced colitis in a mouse model and to explore the possible related mechanisms. Experimental colitis was induced in ICR mice by dissolving 5% DSS in their drinking water for 7 days. Gent (200, 100, and 50 mg/kg) and 5-aminosalicylic acid (5-ASA, 100 mg/kg) were oral administrated once a day for 7 days. Anti-inflammatory effects were evaluated by comparing extend of colonic mucosal injury assessed by disease activity index (DAI), colon length, histopathological examination, and biochemical test. The possible mechanisms of Gent activities were explored by evaluating expression levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6 using real-time fluorogenic PCR and expression levels of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) using Western blotting. The results showed that oral administration of Gent significantly attenuated DSS-induced loss of body weight, diarrhea, shortening of colon length and histological changes, associated with the decrease in the activity of myeloperoxidase (MPO) in the colon. In addition, the mRNA expression of TNF-α, IL-1β, IL-6 and the overexpression of COX-2 and iNOS proteins in the colon were down-regulated by Gent treatment. To our knowledge, this is the first study to demonstrate that Gent treatment can exert anti-inflammatory effects on experimental acute colitis through attenuating the expression levels of TNF-α, IL-1β, IL-6, iNOS and COX-2, and it may present the therapeutic potential in the treatment of colitis.