The work presents the evaluation of longterm results of the surgical prolongation of the femur. The examined group includes 10 patients: 5 boys and 5 girls which the authors treated in the years 1978-1986. Their average age in time of operation was 15.5 years. The youngest was 8 and the oldest 25 years old. Shortening was in 4 cases caused by poor healing of the fracture, in three cases it was a results of congenital hypoplasia of the femur or the whole lower extremity, in three cases it was caused by osteomyelitis. The duration of the prolongation was on average 4 months, the external fixation device was removed on average after 8 months. The mean prolongation was 8 cm, ranging from 4 cm to 11 cm. In 8 cases healing was without complications, twice there occurred a fatigue fracture which was treated by plate osteosynthesis.