The article features the analysis of features of physiological adaptation and the rate of physiological development in boys and girls of preparatory kindergarten groups and 1 – 2 grades of grammar school. The analysis points out the differences of neurodynamic indicators, physiological adaptation and the degree of activity of the autonomic nervous system among 6 – 8 year-old boys and girls. It has been found that, regardless of age, boys are characterized by a lower level of development of mental functions, lower balance of processes of excitation and inhibition in the central nervous system, with faster visual-motor response. They are characterized by a higher degree of tension of regulatory mechanisms. Individuals with symptoms of attention deficit and social-psychological deficits are often detected in this group. Girls display neurodynamic indicators that are most optimal for the corresponding age period, a high level of mental functions development; in this group we observed mainly balanced or parasympathetic influence on heart rate and more satisfactory functional state.