Glutamate (glu), an excitatory amino acid (EAA) abundantly present in the brain of mammals, is also a neurotoxin. We examined lipid peroxidation (LPO) potential and antioxidant parameters of midbrain region (MBR) and frontal cortex of adult rats following treatment with monosodium glutamate (MSG) during postnatal day (PND) 1 through PND 10 at a daily dose of 4 mg g-1 body weight. In PND 90 rats MSG increased LPO by 56% and altered antioxidant status of MBR. This indicates that oxidative stress produced by glu in vulnerable brain regions may persist for prolonged periods and could be one of the mechanisms of EAA neurotoxicity resulting in chronic neurodegeneration.