Objective To evaluate the surgical technique, clinical results, and the complications of modified free vascularized fibular grafting for the treatment of osteonecrosis of the femoral head. Methods From October 2000 to August 2004, 124 patients (139 hips) with osteonecrosis of the femoral head were treated with modified free vascularized fibular grafting. There were 83 males(93 hips) and 41 females (46 hips), with a mean age of 36.4 years(16.57). The disease was caused by trauma in 49 cases(54 hips), use of steroids in 29 cases (32 hips), consumption of alcohol in 19 cases (21 hips) and idiopathic condition in 27 cases (32 hips). Of 139 hips, 50 were classified as stage Ⅱ; 71 as stage Ⅲ, 18 as stage Ⅳ according to Steinberg system; theHarris hip scores were 79.3, 69.3 and 58.4, respectively. At the operation, modified technique of the fibular osteotomy was adopted. A front-hip operative approach was designed and a modified technique of removing the necrotic bone in femoral head was applied. During operation, the duration of operation, the bleeding volume, and the length of incisions were recorded. The follow-up items included the results of X-ray examination, the Harris score of the hip, and the evaluation of the complications. Results The duration of the fibular osteotomy was 10 to 30 min(15 min on average). The duration of the total operation was 80 to 120 min (90 min on average). The length of incision at the hip was 6 to 12 cm (8 cm on average). The bleeding volume was 100 to 300 ml(200 ml onaverage). The average hospitalization days was 7 days. After operation, Harris hip scores in most cases were improved. According to postoperative X-ray, 62 hips (79.5%) were improved to different extents and 14 hips (17.9%) had no significant changes. Deterioration occurred in 2 hips (2.6%). Conclusion The modified free vascularized fibular grafting has lots of virtues, such asless bleeding volume, more clear anatomic structure, more convenience for operation, less damage, less complications, and better results of function recovery.It is an effective method for treating osteonecrosis of the femoral head.