Osteonecrosis of the femoral head is an increasingly common causeof musculoskeletal disability as well as a major diagnostic and therapeuticchallenge. The natural history of this disease is important to understandbecause the rate of femoral head collapse and treatment options arerelated to multiple factors including the cause of the disease, its stage atinitial presentation, and the size and location of the lesion. The results ofnew pharmacologic and biophysical treatments appear beneficial indelaying, and possibly preventing, the progression of precollapse lesions.New bone grafting strategies may enhance the results of coredecompression. Nonoperative treatments include protectedweightbearing, physical therapy and pharmacologic treatments. Operativetreatment includes core decompression with or without grafting,osteotomy, hemiarthroplasty, hemiresurfacing, total resurfacing and totalhip arthroplasty.