Aims: The etiology of autism spectrum disorders (ASD) remains elusive, but oxidative stress has been suggested to play a pathological role. The understanding of the potential role of oxidative stress in the etiopathogenesis of autism would be very useful for earlier clinical, therapeutic or preventive strategies. Sample: To evaluate the redox status, we quantified the activity of the antioxidant enzyme catalase (CAT), glutathione concentration (GSH) and markers of damage to biomolecules, malonyldialdehyde (MDA) and 8–hydroxy-2deoxyguanosine (8OHdG) in peripheral blood samples. Place and Duration of Study: Sample: Department of Neuropediatrics and Technology Science Division. International Center for Neurological Restoration (CIREN), Havana, Cuba. May 2011- June 2012. Methodology: We included 45 children with autism (36 males and 9 females, age-range from 3 to 11 years). 42 children of the same age were selected as a control group. The diagnosis of autism was made based on the criteria of autistic disorders as defined in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM IV) (American Psychiatric Association, 1994). Results: The total GSH content in autistic patients was significantly lower compared with the control group (0.24 ± 0.162 vs. 0.94 ± 0.115, respectively, p ≤ 0.001). Higher serum CAT, MDA and 8OHdG levels were found in children with autism compared with controls (CAT, 2.836 ± 0.479 vs. 0.689 ± 0.157, p ≤ 0.001; MDA 8.6 ± 0.5 vs. 1.76 ± 0.33 p ≤ 0.001, and 8OHdG 13.134 ± 1.33 vs.1.46 ± 0.326, p ≤ 0.001). Conclusion: The present study supports the notion that oxidative stress is associated with autism, but additional researches are needed to investigate how it may contribute to autistic pathophysiology and these studies are currently in progress.