In this study, 50 children between 3 and 12 years old with formally diagnosed autistic spectrum disorders (ASD) and also having significant mitochondrial dysfunction will be treated for a 3 month period with the Mitochondrial Cocktail, a combination of specific nutritional supplements and metabolite intermediates (including anti-oxidants) and bio-energy substrates. The Mitochondrial Cocktail is presently widely used as the standard of care for clinically treating mitochondrial dysfunction.