Ipsilateral femur and tibia fractures - so called "floating knee" are caused by high energy trauma and frequently associated with many problems such as hemorrhagic shock, higher morbidity, delayed union, knee stiffness, etc. To get a satisfactory functional result, rigid internal fixation and early mobilization are regarded as treatment priciples at present. Authors analyzed the functional outcomes of floatinhg knee injuries according to the fracture type and methods of surgical treatments. Twenty-eight patients were diagnosed as ipsilateral femur and tibia shaft fractures and treated surgically at the Dongguk University Hospital between June 1990 and May 1996. Average age was 34.5 years, and males were predominant. Majority of cases (27 out of 28) were caused by traffic accident. According to the classification of Blake and McBryde, type I injuries were observed in 17 cases and type II in 11 cases. Average follow up period was 1.3 years. All patients were treated by surgical methods which were selected appropriately with concideration of fracture types. 14 of 17 type I injuries were treated with intramedullary nailing for both femur and tibia fractures. Among these cases, 9 were excellent and 4 were good results. But in type II injuries, only 3 of 4 cases which were fixed with intramedullary nailing for femur and plate for tibia fractures were good results. Conclusively, Intramedullar nailing is an excellent method for ipsilateral femur and tibia fracture and type II injuries which have intra-articular fracture lines meet with worse results than type I.