The important part in evaluating the biological age of the child is to determine the bone maturity state. The so called "bone age" in healthy individuals of the same sex does not differ and it is the only known index in the development of the child since birth until the termination of growth. The X-ray picture of the hand and wrist showing a number of bones in a small area proved to be useful for such purpose. The picture makes it possible to reveal potential congenital anomalies and other pathological changes of the visualized skeleton and a comparison of the state of bone maturation with the years of age of the patient. In the routine practice of most radiodiagnostic workplaces the GP method proved to be sufficient (according to Greulich and Pyle). For specialized clinical workplaces, where an absolute precision of evaluation is necessary, the TW3 method was reported as most useful (according to Tanner and Whitehouse), corrected by the GP method at best. Both these methods well correspond to maturation of skeleton of the present population of Czech children. The criteria of TW2 method correspond to children who mature later than the present Czech children.

        Key words: bone maturation - bone age - present children population - imaging met¬hod