BACKGROUND The period of the constitutional transformation, apart from many advantages, has generated a number of serious problems that may affect the biological state of children and adolescents in Poland. OBJECTIVE The study documented socio-economic differentiation of growth and dietary intake of boys. METHODS The research involved 523 boys aged 7-16; 54.4% of subjects came from Kielce (a city with a population of over 200 000) and 45.6% came from rural areas - from a region underprivileged in terms of economic development, with a majority of its inhabitants living off the land. Height and weight measurements of the subjects were taken, which allowed for computation of BMI. Dietary intake was assessed using the interview method for 24 h dietary recall. A multifactor variance analysis for unequal numbers in subclasses was applied to estimate the influence of socio-economic factors such as place of residence, mother's education and number of children in the family on somatic traits and on nutrient intake. RESULTS Urban boys whose mothers had experienced higher education were characterized by the greatest height (p<0.000). The percentage of the investigated subjects with an excessive body mass was over twice as high among boys in families with one or two children (15.0%) than among boys in families with three or more children (6.1%), and twice as high among urban boys (14.1%) in comparison with rural boys (7.0%). No significant differences in the energy value of daily food intake in each social group were found. The diet of rural boys included a lower percentage of energy intake derived from protein (10.7%) than that of urban boys (12.4%). This percentage decreased together with the lowering level of mother's education. The greatest amount of minerals and vitamins was found in the diets of boys whose mothers had higher education and lived in a city. CONCLUSIONS Diets of boys with the greatest body height were also characterized by a greater content of mineral components and vitamins, and a greater percentage of energy derived from protein. The relative body mass of the investigated subjects was probably more influenced by factors other than nutrition, i.e. mostly physical activity.