The present research aimed at the comparative analysis of studies on early detection and epidemiology of mental disorders in young children in Russia and other countries. Epidemiological data are presented for mental, behavioral and developmental disorders (MBDDs), including autism spectrum disorders (ASD), in children aged 1848 months in general child population in nine large Russian regions. The prevalence of the risk for MBDDs is 1307:10,000 (13.07%), the prevalence of clinically verified cases of MBDDs is 151:10,000 (1.51%), and the prevalence of ASD among them is 18:10,000 (0.18%). The average estimations are close to that obtained by Belarusian, Danish, and China investigators among corresponding national populations, but lower than estimations in US. The differences are due to the different methodological approaches to epidemiological estimations of the prevalence, including clinical, psychometrical, and other evaluations. The screening of the risk for MBDDs, including ASD in Russia among children in the general pediatric population is a promising area of preventive medicine.