The "floating knee" is the term applied to the flail knee joint segment resulting from a fracture of the shaft of adjacent metaphysis of the ipsilateral femur and tibia. The treatment of ipsilateral femur and tibia fracture was difficult and functional result was poor in most cases. Authors treated 30 fractures of femur and tibia on same leg from April 1986 to January 1990. The results were as follows;1. The incidence of trauma was high in the young man and the peak age was fourth decade. 2, The most common cause of fractures was traffic accident; 27 patient (90% ) 3. The common fracture site were middle one third and the most common fracture shape was comminuted in both femur and tibia. 4. The most common associated injury was head trauma;6 cases. 5. The average healing time of fracture was 22.5 weeks in femur and 23 weeks in tibia of the rigid internal fixation group. 6. A good or excellent functional result was achieved in treated with open reduction and rigid fixation of both fracture.