Peroxynitrite ($ONOO^-$), superoxide anion radical (${\cdot}\;{O_2}^-$) and nitric oxide (NO) are cytotoxic because they can oxidize several cellular components such as proteins, lipids and DNA. They have been implicated in the aging processes, and age-related diseases such as Alzheimer's disease, rheumatoid arthritis, cancer, diabetes, obesity and atherosclerosis. The aim of this study was to investigate the effects of Ojunghwan on the generation of peroxynitrite ($ONOO^-$), nitric oxide (NO) and superoxide anion radical (${\cdot}\;{O_2}^-$), and on the expression of $NF-{\kappa}B$-dependent inflammatory proteins in ob/ob mice. Mice were grouped and treated for 5 weeks as follows. Both the normal lean (C57/BL6J black mice) and control obese (ob/ob mice) groups have received the standard chow. The experimental groups were fed with a diet of chow supplemented with 30 and 90 mg Ojung-hwan per 1 kg of body weight for 14 days. For this study, the fluorescent probes, namely 2',7'-dichlorodihydrofluorescein diacetate (DCFDA), 4,5-diaminofluorescein (DAF-2) and dihydrorhodamine 123 (DHR 123) were used. Western blot was performed using anti-phospho $I{\kappa}B-{\alpha}$, $anti-IKK-{\alpha}$, $anti-NF-{\kappa}B$ (p50, p65), anti-COX-2, anti-iNOS, anti-VCAM-1 and anti-MMP-9 antibodies, respectively. Ojunghwan inhibited the generation of $ONOO^-$, NO and ${\cdot}\;{O_2}^-$ in the lipopolysaccharide (LPS)-treated mouse kidney postmitochondrial fraction in vitro. The generation of $ONOO^-$, NO, ${\cdot}\;{O_2}^-$ and $PGE_2$ were inhibited in the Ojunghwan-administered ob/ob mice groups. The GSH/GSSG ratio was decreased in the ob/ob mice, whereas that were improved in the Ojunghwan-administered groups. Ojunghwan inhibited the expression of $phospho-I{\kappa}B-{\alpha}$, $IKK-{\alpha}$, $NF-{\kappa}B$ (p50, p65), COX-2, iNOS, VCAM-1 and MMP-9 genes. These results suggest that Ojunghwan is an effective scavenger of $ONOO^-$, ${\cdot}\;{O_2}^-$, NO and $PGE_2$, and has an inhibitory effect on the expression of $NF-{\kappa}B$-dependent inflammatory genes in ob/ob mice. Therefore, Ojunghwan might be used as a potential therapeutic drug against the inflammation process and inflammation- related diseases.