Within the general evaluation of the validity of the index of body bund development (KEI) as a criterion of biological Proportional age the authors investigated the information it Provides for the diagnosis of the develoPmental trend in the subpopulation of obese and overweight Children. They confirmed that the information Provided by KEI on the type of the child's maturation is very valuable. The index of the body bund development diagnosed sensitively, consistent with the normal child PoPulation, all three developmental trends - accelerated, average and retarded development.

        Key words: biologcckl Proportional age, index of body bund development (KEI), overweight Children,