GyeongshinhaeGihwan T1 (GGT1) is a newly developed oriental medicine to help weight control. We investigated nitric oxide production and cytokine secretion in mouse peritoneal macrophages. According to recent reports, macrophages are participated in fat accumulation and closely related with obesity. In this study, using mouse peritoneal macrophages, we have examined whether GGT1 affects the production of nitric oxide (NO), tumor necrosis factor-${alpha}$ (TNF-${alpha}$), and interleukin (IL)-12 by the stimulation of interferon-${gamma}$ and lipopolysaccharide (LPS). GGT1 inhibits LPS-induced NO production in a dose-dependent manner. The decrease in NO synthesis was reflected as a decreased amount of inducible NO synthese protein. We also found that GGT1 inhibits pro-inflammatory cytokines, TNF-${alpha}$ and IL-12 production. In mouse embryo preadipocyte 3T3-L1, GGT1 reduced the viability in a dose-dependent manner. These findings suggest that GGT1 may have potential effects in preventing and controlling adipogenesis and obesity.