We aimed to explore the anti-inflammatory activity of mollugin extracted from Rubia cordifolia L, a traditional Chinese medicine, on dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in mice. Thirty C57BL/6 mice were divided into a control group (n=6), a model group (n=6), and three experimental groups (40, 20, 10 mg/kg of mollugin, n=6 each). DSS solution (3%) was given to mice in the model group and experimental groups from day 4 to day 10 to induce the mouse UC model. Mice in the experimental groups were intragastrically administrated mollugin from day 1 to day 10. Animals were orally given distilled water in the control group for the whole experiment time and in the model group from day 1 to day 3. The changes in colon pathology were detected by hematoxylin and eosin (HE) staining. Interleukin-1 beta (IL-1 beta) in the serum, and tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN) in the tissues were measured by enzyme linked immunosorbent assay. Expression levels of Toll-like receptor 4 (TLR4) and myeloid differentiation factor 88 in the colon tissues were detected by immunohistochemistry. Results showed that mollugin could significantly reduce weight loss and the disease activity index in the DSS-induced UC mouse model. HE examinations demonstrated that mollugin treatment effectively improved the histological damage (P0.05). The overproduction of IL-1 beta and TNF-alpha was remarkably inhibited by mollugin treatment at doses of 20 and 40 mg/kg (P0.05). Additionally, the levels of TLR4 in colon tissues were significantly reduced in mollugin-treated groups compared with the DSS group. Our findings demonstrated that mollugin ameliorates DSS-induced UC by inhibiting the production of pro-inflammatory chemocytokines.