The effects of gamma-irradiation on inflammatory gene expression, including NF-kappa B activation, in the kidney of C57/BL6 mice exposed to 1-9 Gy doses of Co-60 gamma-irradiation. Radiation enhanced the NF-kappa B activation and oxidative stress caused a dose-dependent disruption in the redox balance. The significance of this study is the new molecular information gained on gamma-irradiation effects through the activation of pro-inflammatory genes by NF-kappa B via the MAPK signaling pathway. Considering the exquisite sensitivity of NF-kappa B and other pro-inflammatory mediators to the redox status, we conclude that the activation of inflammatory processes by irradiation is likely initiated by increased oxidative stress.