To elaborate unified criteria for the physical development evaluation in children, a comparison was made of two populations of children in the Estonian SSR: with normal and excessive body mass (EBM). The investigation was conducted by the cohort type, the children were divided into groups according to their age, sex, residence and nationality. To study the influence of the above factors on the distribution of Quetelet's index (the basic parameters of EBM) in the population of children in the Estonian SSR, a criterion was used, characterizing variations of the populations with respect to each of the factors with due regard for the rest factors. It has been established that in the evaluation of the physical development of children the differences in the distribution of Quetelet's index should be considered taking into account sex, nationality and residence of children.