Aims: The late effect of intramedullary nailing of the femur on proximal femur growth, particularly on growth plate of the greater trochanter and femoral neck, being known that losing the balance in the growth of the three ossiþcation points of the femurñs proximal extremity, the gap canñt be compensated by the greater trochanterñs remaining growth cartilage. Methods: During 1980–1995 we have performed 55 intramedullary femoral osteosyn-theses using KŸntscher rods in children 5–14 years of age. We have had the opportunity to observe 29 children during their later somatic growth: 25 femoral diaphyseal fractures and 4 non-unions. The average folow-up period has been 8.3 years. The patientñs average age has been 9,5 years. The hips were evaluated clinically for walking, mobility, limb length discrepancy. Radiological evaluation was based, according to Edgren, on following parameters of the joint architecture: cervico-diaphyseal angle (CDA), articulo-trochanteric distance (ATD), intertro-chanteric distance (TTD), femoral neck diameter (FND). Results: Clinical, one child presented 1.3 cm femur shortening. The evaluation of the radiological parameters on coxo-femoral joint showed increased CDA value between 10–30¡ in 8 children, increased ATD value (10–20mm) in 7 children, reduction of the TTD value in 6 patients and reduction of the FND (5–10mm) in 3 children. Conclusions: Insertion of intramedullary nail via the greater trochanter should be avoided in children less than 13–14 years of age, having tardy valgus effect and thinning of the femoral neck. We recommend osteosynthesis with plate and screws or, in little ones, transfragmentar screws, followed by immobilisation in plaster cast.