Aim: Femoral and tibial fractures with instability of length, rotation and angulation are the ideal indications for interlocking nails. Traditional treatment has been traction or cast bracing. Unfortunately, the use of these techniques typically led to a high rate of malunion and knee stiffness. The advent of plate þxation improved both alignment and knee motion but resulted in a high rate of infection, nonunion and implant failure. Material and Method: 38 patients (27 men and 11 women) with complex femoral and tibial fractures have been treated with locked IM nail during the period 1997–2001. The age of the patients was between 17–85y. There were 19 patients with femoral fractures and 17 with tibial fractures. The im nails that have been used are: 22 Rusel Taylor, 11 Orthoþx, 3 DLS, 1 GK, 1 Citeffe. Results: The mean time for bone union formation that was needed in order for the patient to return in full activity was 4.8 months (4–12). The þnal result was based in (1) Bone union, (2) function of hip, knee and ankle, (3) Axial deviation, (4) Shortening-lengthening,(5) Deep inßammation, (6) Constant pain of patelofemoral articulation. Excellent results were noted in 33 patients (87.1%), good in 3 patients (8.1%) and poor in 2 (4.8%). Conclusion: Use of the locked femoral and tibial nail inserted with closed technique must become the standard of care for treatment of comminuted (B or C type) fractures but demands experience on the part of the surgical team.