In cases of the congenital dislocation of the hips neglected without proper treatments at their childhoods or young ages, or in cases of pyogenic or tuberculous arthritis of the hips of the infants or childhoods, hip deformities could be developed, and they could lead to serious disabliies, and many difficult problems could be found in treating them. In such deformities of the childhoods or young adults, the patients are usually not so painful but serious physical and social disabilities such as severe limping, leg length discrepancy and psychological depression could be presented. The total hip joint replacements and arthroplasties in such cases could have many difficult problems, because the femoral head and the acetabulum are not developed normally and are not in normal position, and contractures of the soft tissues and muscles around the hip joint could be existed. Even if the successful arthroplasties could be achieved, revision arthroplasties should be needed in several years. Also the total hip joint replacements and arthroplasties could not correct the severe leg length discrepancy. Ilizarov suggested the method of hip reconstruction, in which by the valgus osteotomy of the subtrochanteric region of the femur, the tension of the gluteus medius could be restored and the unstable hip could be converted to the stable hip, and the leg length discrepancy could be corrected by the lengthening of the shagt of the femur, and mechanical axis, flexion or extension contracture of the hip could be corrected simultaneously. It is thougth to be a permanent procedure that needs not revision arthroplasty, because it is not an arthroplasty using endoprosthesis but a biological reconstruction using the hip joint and the femur of the patient himself. Authors experienced of cases of the hip reconstruction and femoral lengthening by principle of he ilizarov treatment, and authors report them.