Background. Autism is a spectrum of neurodevelopmental disorders with manifestation within 3 years after birth. Manifestations of autism include behavior problems (hyperactivity, toys destruction, self-harm, and agression) and sleep and eating disorders. Etiology of autism is poorly understood. Oxidative stress and antioxidants can participate in pathobiochemical mechanisms of autism. Methods. Twenty-four children, aged 3-6 years, with autism according to the DSM IV criteria and using CARS were included in the study. Concentrations of CoQ(10-TOTAL), gamma- and alpha-tocopherol, beta-carotene, and lipid peroxidation were determined in plasma before and after three months of supportive therapy with ubiquinol at a daily dose 2 x 50 mg. Data on behavior of the children were collected from parents at the same time. Results. Ubiquinol supportive therapy improved symptoms in children with autism, as communication with parents (in 12%), verbal communication (in 21%), playing games of children (in 42%), sleeping (in 34%), and food rejection (in 17%), with CoQ(10-TOTAL) plasma level above 2.5 mu mol/L. Conclusions. Beneficial effect of ubiquinol in children with autism has been demonstrated for the first time. We assume that plasma concentration of CoQ(10-TOTAL) and lipid peroxidation could be used as relevant biomarkers of ubiquinol supportive therapy.