Authors performed Ilizarov treatment for 9 cases of severse knee flexion contracture. The causes of knee flexion contracture were 2 cases of rheumatoid arthritis, 2 cases of malunion of tibia and femur, 2 cases of infection sequelae, and 3 cases of hemophilic arthritis. The preoperative flexion contracture was av. 65.6 degrees(40-90 degrees). We started the correction at postoperative av. 3.88th day(2-12th day) after postoperative pain was controlled. After the deformity was corrected, the frame was left in place for av. 16.6 days(6-42 days). But in 2 cases of malunion of tibia and femur and 1 case of infection sequela, angular deformity and leg length discrepancy were managed after the correction of knee flexion contracture. The postcorrection flexion contracture was av. 2.6 degrees(0-10 degrees). The correction rate was av. 1.71 degrees/day(0.57-4.16 degrees/day) and the duration for correction was av. 51.1 days(12-85 days). After the follow-up period of av. 7.6 months from removal of Ilizarov, flexion contracture was av. 10.0 degrees(0-25 degrees). We conclude that the severe flexion contracture of the knee can be treated successfully with the Ilizarov correction. Limb shortening and neurovascular injuries can be avoided or minimized with the Ilizarov correction for flexion contracture of the knee as apposed to the other method. The recurrence of the flexion contracture of the knee may be prevented with the sufficient maintenance period.