Inflammatory bowel disease (IBD) is characterized by detrimental immune reactivity in the gut, and the imbalance between proinflammatory and anti-inflammatory reactivity. The incidence and prevalence rates of IBD in Korea have been increasing rapidly during the past decades. In this study, we investigated regulatory effect of leaf of a mulberry tree (Moraceae) called Gwasang-No.2 in Korea. Leaf of Gwasang-No.2 (Gwa.L) inhibited the inflammatory responses on dextran sulfate sodium induced ulcerative colitis in mice and the production of nitrite oxide from lipopolysaccharide and interferon-gamma stimulated mouse peritoneal macrophages. Gwa.L inhibited IL-6 and IL-8 production from HMC-1 cells without cytotoxic effects on cell viability. These results may be relevant for future pharmacological or dietary interventions in patients with ulcerative colitis.