Aims: Lengthening of bones with Ilizarov method is acknowledged method as well very inconvenient. First inconvenience is long lasting of immobilization in external stabilizer, responsible for joints contracture and muscles atrophy. Use of interlocking nail makes possible removal of stabilizer immediately after finishing of lengthening without risk of deformity of fresh bone callus. Methods: From 1999 to 2001 we used this method in the treatment of 11 patients age 13–23 years [~16,9], with shortening of femur 3–8 cm [~4,9]. Etiology of shortening was: congenital [8], aseptic necrosis of femoral head [2] and comminuted fracture of femoral shaft [1]. During surgery we cut cortex of femur, than interlocking nail and finally external stabilizer were applied. After we reached planned lengthening nail was locked and stabilizer was removed. For complications we used Paley classification. Results: We received planned length of femur in 10 cases. Average time of applying of external stabilizer was 14 days/1cm of lengthening. Problems: fracture of femoral shaft without displacement during driving of the nail [1], pin site infection of soft tissues and transient restriction of movements of knee in all cases. Obstacles: wedging of the nail [2], fracture of femur after removal of the nail [1] and deep infections along the nail [1]. Complications: shortening of femur about 0,6 cm because of premature rebuilding of bone callus [1]. Conclusions: Advantage of this method is decrease of complications thanks to shortening of time of immobilization in external stabilizer, inconveniences are: more extensive surgery, risk of wedging of the nail and fracture after removal of the nail because of weak bone callus.