Since June 1987, were realized 45 limb lengthening (40 lower and 5 upper) in 34 children with between 3-15 years old. A dynamic axial fixator (DAF) system with telescoping capabilities, permits a slow distraction through a osteotomy and callotasis in 36 bones, and chondrodiatasis in 5. Twenty-six unilateral lengthening were realized and 5 alineation-lengthening, 20 congenital and 11 acquired causes. 14 bilateral lengthening were done in 5 patients (4 achondroplastic and one Turner's syndrome). The average increase in length was 5.5 cm. for limb and ranged from 4.3 to 8.0 cm. The healing index was 32.1 days for each centimeter of length gained in the femurs and 5.2 cm. with 28.2 days/cm. in the tibias. The complications were superficial pin tract infection (73%), that were not generally treated with antibiotic, 2 knee valve, 2 knee subluxation and one patella subluxation with knee flexion contracture.