In 1973, Steel described triple innominate osteotomy in which the ischium, the superior pubic ramus and ilium superior to the acetabulum are divided and the acetabulum is repositioned anterolaterally and is stabilized by a bone graft and metal pins. Its goal is to establish a stable hip for dislocation or subluxation of the hips in older children and adults on whom it is impossible to correct effectively the instability by any one of the more conventional osteotomies, i.e. Salter's, Pemberton's or Chiari's, or by the capsular arthroplasty of Colonna. During the eleven years and eight months, from December 1973 to August 1985, at the Department of Orthopedic Surgery, Seoul National University Hospital, we performed Steel's triple innominate osteotomy on 41 cases, of which 37 were residual poliomyelitis and 4 septic hip residua. 4 cases of residual poliomyelitis were lost during follow up. The remaining 37 cases were reviewed for the efficacy and limitations of triple innominate osteotomy. We observed following conclusions: 1. Aside from congenital dislocation and dysplasia of the hip, paralytic conditions, such as residual poliomyelitis, are good indications of Steel's triple innominate osteotomy in older children, adolescents and young adults. Acetabular acclivity is adequately reduced and stability is improved. 2. Septic hip residua, including healed tuberculosis, is another indication of triple innominate osteotomy, particularly when total hip arthroplasty is contemplated. 3. When abductors are partially paralyzed, triple innominate osteotomy alone results in appreciable increase in abductor power, by providing a better muscle tension. 4. Substantial gain in leg length is an added advantage of triple innominate osteotomy. An average of 1.74 cm was gained at osteotomy site in our series. In adults, when limb shortening is relatively m i nor, triple innominate osteotomy alone can be a more convenient alternative to conventional, more formidable method of leg length equalization, such as femoral lengthening. This is particularly true when there is some instability or when abductors are weak. 5. Following improvement in mechanical stability by triple innominate osteotomy, weak abductors and extensors may be augmented by appropriate muscle transfer, resulting in more stable hip functionally. 6. In a hypermobile paralytic hip, iliopsoas tenotomy is neither necessary nor desirable at the time of osteotomy. When the hip is dislocated, or when the hip has marked flexion deformity, iliopsoas tenotomy fascillitates adequate correction, but this greatly increases the risk of neurological complication.