Recently, intramedullary nailing has been used classically in a closed transverse fracture in middle one-third of the fernur. But difficult femorsl fracture, such as severe comminution or nonunion, present a much more difficult problem. To treat these difficult femur fractures effectively, several investigators have developed and implemented a interlocking nail. Huckstep nail, one of the variants of the inter-locking nail, is a solid four sided intramedullary nail with screw fixation device and titanium alloy. For the purpose of rigid fixation and compression, screw fixation the nail and both cortice has been used in the difficult femorsl fractures. The author have experienced the 19 cases of Huckstep nailing for the treatment of difficult femoral fracture at the Choongahng Gil Hospital from Jan., 1984 to Dec., 1987. The results are summarized as follows. 1) In the difficult femoral fractures, such as fracture on severe comminuted fracture, nonunion and metal failure etc, Huckstep nailing may be excellent fixation. 2) Open comrninuted femoral frsctures were treated by conservative treatment as antibiotic therapy and skeletal traction, but when general conditions return to normal and risk of infection rate minimized, Huckstep nailing should be done. This generally requires 4 to 6 weeks. 3) The mean duration of bone union was 21.2 weeks. 4) Early joint mobilization can be done. The results of 17 cases were excellent by Denker's criteria. 5) Important complication were metal failure with refracture, screw failure and refracture after extraction of nail, these were caused by incorrect placement of nail, incorrect length of nail and more rapidly early weight bearing. 6) Nail of 11.5 mm in diameter is suitable in our study.