The purpose of this study was to evaluate the results and complications in difficult periarticular fractures of the knee treated with a circular(Ilizarov) external fixator. The mean follow-up period was 34 months(range: 12-55 months). Of the 27 cases, 12 cases involved fractures of distal femur (two M ller type A3, four type C2, six type C3) and 15 cases involved fractures of the proximal tibia (one Schatzker type V, eight type VI, two segmental, four metaphyseal comminuted fractures). Twenty-two cases(81%) were open fractures and most of the cases were open intra-articular comminuted fractures. The average duration of external fixation was 7.7 months (9.8 months for the distal femur cases, 6.5 months for the proximal tibia cases and 11.5 months for the cases which required lengthening, and 6 months in the non-lengthening group). In 8 cases, in which bone lenthening was done, no leg length discrepancy occurred after lengthening. The mean length gained was 5.9 cm and the mean healing index was 1.8 months/cm (1.8months/cm in distal femur cases and 1.9 months/cm in proximal tibia cases). According to Neers criteria, the treatment results for cases involving distal femur fracture were as follows: six satisfactory, three unsatisfactory, three failures; cases with proximal tibia fractures had these results: nine excellent, three satisfactory, three unsatisfactory. Average range of motion was 67 degrees in distal femur fracture cases and 114 degrees in proximal tibia fracture cases. According to Paleys complication grading system, six problems, six obstacles, and eight com- plications occurred. In conclusion, the Ilizarov external fixator can be a useful treatment method in periarticular fractures of the knee with severe intra-articular or metaphyseal comminution, bone loss, severe soft tissue injury, or multiple associated injury. Its use can reduce the associated complications such as leg length discrepancy, infection, and nonunion.