The expression of a variety of proteins is elevated with aging through unknown mechanisms. The free radical theory of aging promulgates that reactive oxygen species (ROS) promote the aging process. However, the mechanisms as to how ROS contribute to the aging process are not clear. We present data here that demonstrate that aging induced ROS promote aging-associated interleukin-6 (IL-6) gene transcription in mice that are transgenic for the murine IL-6 promoter driving a luciferase reporter cDNA. N-acetylcysteine (NAC), an antioxidant, completely reverses the increased endogenous IL-6 promoter activity in the old mice determined by real-time bioluminescence imaging (BLI). We conclude that ability of ROS to act as secondary messengers and induce gene expression may contribute to the aging process.