Abstract The effect of l-carnitine on lipid peroxidation and antioxidant status has been studied in blood, liver, and kidney of young and aged rats. In the aged rats, level of lipid peroxidation was considerably high, while the antioxidants superoxide dismutase, catalase, glutathione peroxidase, vitamin C, and vitamin E reduced glutathione, and total thiols were low. The l-carnitine was administered by i.p. injection (300 mg/kg body weight/day) for 7, 14, and 21 days. Supplementation of aged rats with l-carnitine demonstrated a time-dependent normalization of abnormally elevated lipid peroxides and of subnormal antioxidant status. Carnitine administration to young rats has brought reduction in lipid peroxidation and elevation in glutathione peroxidase activity and ascorbic acid content. From our observations we conclude that as carnitine is very effective in normalizing age-associated alterations, it can be implemented in the aged to minimize age-associated disorders where free radicals are the major cause.