A modification of the triple pelvic osteotomy for children over 8 years and the young adult is described. The results of the first 32 cases are reviewed. These show that the indications for the operation can be widened so that not only primary dysplasias but also subluxated or dislocated hips with secondary dysplasia can be operated on successfully. The operation is done in two stages. At first the patient is lying prone. The osteotomy of the ischial ramus is done dorsally by cutting the connection between the sciatic notch and obturator foramen immediately behind and below the acetabulum. In the second stage, with the patient lying supine, the pubic and the iliac osteotomy are performed rather circular and parallel to the hip joint. These modifications have several advantages: (a) the operator has a direct field of view at all times; (b) the osteotomy is performed close to the acetabulum, thus allowing a great amount of lateral rotation and medial displacement of the acetabulum, thereby providing good coverage of the femoral head by hyaline cartilage; and (c) the ischial ramus and its ligaments to the sacrum are left intact, leading to greater stability of the pelvis and spine.