Paeoniae Radix has been used as a traditional medicine for various diseases including hepatic disease. However, the inhibitory effect of Paeoniae Radix on intestinal inflammation has not been fully understood yet. The aim of this study was to evaluate the effect of Paeoniae Radix on colitis induced by dextran sulfate sodium in mice. To investigate the protective effects of Paeoniae Radix, the colitis mice were induced by drinking water containing 5% dextran sulfate sodium for 7 days. Mice were randomized into groups receiving Paeoniae Radix (100 ㎎/㎏), sulfasalazine (150 ㎎/㎏) as a positive control, or water as a negative control. We evaluated the effects of Paeoniae Radix on clinical signs induced by dextran sulfate sodium, measuring weight loss, colon length, and disease activity index. Additionally, to find a possible explanation for the anti-inflammatory effects of Paeoniae Radix, we evaluated the effects of Paeoniae Radix on the interleukin-6 and cyclooxygenase-2 levels in colitis tissue. The results indicated that mice treated with dextran sulfate sodium showed measurable clinical signs, including weight loss and reduced colon length. However, Paeoniae Radix treatment significantly improved the weight loss and disease activity index as clinical symptoms. Moreover, Paeoniae Radix inhibited the interleukin-6 and cyclooxygenase-2 expression levels in colon tissues treated with dextran sulfate sodium. Taken together, the findings of this study suggest that Paeoniae Radix may be useful for treating intestinal inflammation, including ulcerative colitis.