Osteonecrosis of the femoral head may lead to progressive destruction of the hip joint. Although the etiology of osteonecrosis has not been definitely delineated, risk factors include corticosteroid use, alcohol consumption, trauma, and coagulation abnormalities. Size and location of the lesion are prognostic factors for disease progression and are best assessed by MRI. The efficacy of medical management of osteonecrosis with pharmacologic agents and biophysical modalities requires further investigation. Surgical management is based on patient factors and lesion characteristics. Preservation of the femoral head may be attempted in younger patients without head collapse by core decompression with vascularized bone grafts, avascular grafts, bone morphogenetic proteins, stem cells, or combinations of the above or rotational osteotomies. The optimal treatment modality has not been identified. When the femoral head is collapsed, arthroplasty is the preferred option.