Aging, Antioxidants, Skeletal muscle.During aging, skeletal muscle is subjected to progressive loss of muscle mass and strength (sarcopenia) and a decline in the functional ability. The reduction in the antioxidative capacity of the skeletal muscle resulting in an abnormal accumulation of the reactive oxygen species (ROS) that is one of the possible causes of the decline in muscle performance. In this study the histological changes in the soleus muscles of male mice at the age of 1 st and 15 th old were examined and the activities of the antioxidant enzymes, CAT and SOD, non-enzymatic antioxidant GPH and MDA level were measured to clarify the age-related changes in healthy subjects. Results showed that there is a significant reduction (P ≤ 0.05) in the antioxidants SOD, CAT and GPH and there is a significant increase (P ≤ 0.05) in MDA level at the age of 15 th month when compared to 1 st month old. We concluded that the activities of the antioxidants were affected by aging. Moreover, there is age-related lipid peroxidation.