This study evaluates the effect of transcranial magnetic stimulation (TMS; 60 Hz and 0.7 mT) treatment on 3-nitropropionic acid (20 mg/kg i.p./day for 4 days)-induced oxidative stress in cortical synaptosomes of Wistar rats. The oxidative derangement was confirmed by a high level of lipid peroxidation products and protein carbonyls, together with a decreased in reduced glutathione (GSH) content, catalase and GSH-peroxidase (GSH-Px) activities. Additionally, it was observed a reduction in succinate dehydrogenase (SDH) activity. All changes were partially prevented or reversed by administration of TMS. These results show that TMS reduces oxidative stress in cortical synaptosomes, and suggest that TMS may protect neuronal and maintain synaptic integrity.