Introduction. Advanced stage and a large area of necrotic bone are known risk factors for failure after transtrochanteric rotational osteotomy of the hip in patients with osteonecrosis. The purpose of this study was to determine whether there were other risk factors for failure of this osteotomy. Methods. One hundred and five patients (113 hips) underwent transtrochanteric anterior rotational osteotomy for femoral head osteonecrosis and were followed for a mean period of 51 months post-operatively. Radiographic failure was defined as secondary collapse or osteoarthritic change. Multivariate analysis with the use of a