The Hungarian National Growth Study comprises data on 39,035 children and youth aged 3–18 years. We examine the relationship between 15 body measurements and nine family background variables in this data set. After multiple regression analysis which removed curvilinear age effects, family size and population size of the place of residence showed consistent associations with the body measurements. Children from larger families tended to be shorter on average, and have lower weight and skinfold thicknesses whereas children from Budapest were, on average, taller and heavier than children from elsewhere with bigger chest and calf circumferences and lower skinfold thicknesses. Paternal age, mother’s profession and birth order showed few associations with body measurements in both sexes and father’s profession did not associate significantly with any of the measurements in boys.