Objective To investigate the effectiveness of free vascularized fibula grafting with unilateral fibula as donor in treatment of bilateral avascular necrosis of femoral head (ANFH). Methods Between June 2007 and January 2008, 14 patients with bilateral ANFH were treated with free vascularized fibula grafting with unilateral fibula as donor. There were 12males and 2 females with an average age of 36.6 years (range, 17-57 years). The necrosis was caused by use of steroids in 3 cases, consumption of alcohol in 4 cases, and idiopathic condition in 7 cases. According to Steinberg system, 16 hips were classified as stage II, 10 hips as stage III, and 2 hips as stage IV. The preoperative Harris hip scores were 77.50 ± 4.19, 69.70 ± 2.76, 59.50 ± 0.50 in patients at stages II, III, and IV, respectively. The duration of operation and the bleeding volume were recorded. The X-ray examination, the Harris hip score, and the compl ications were used to evaluate the effectiveness. Results The duration of the fibula osteotomy was 10-32 minutes (mean, 20 minutes). The duration of the total operation was 100-240 minutes (mean, 140 minutes). The bleeding volume was 200-500 mL (mean, 280 mL). All patients achieved heal ing of incision by first intention. The patients were followed up 12-40 months (mean, 24 months). One case had numbness and hyperthesia of the anterolateral thigh; 1 case had abnormal sensation of the dorsal foot; 1 case had discomfort of the ankle; and they restored to normal at 1 year after operation. According to X-ray films 1 year after operation, the improvement was achieved in 23 hi ps (82.1%) and no deterioration in 5 hips (17.9%). At 1 year after operation, the Harris hip scores were 93.90 ± 4.84, 88.50 ± 8.13, and 78.00 ± 0.00 inpatients at stages II, III, and IV, respectively, showing significant differences when compared with preoperative ones (P lt; 0.05). Conclusion Unilateral free vascularized fibula grafting has lots of virtues, such as short surgical time, less bleeding volume, l ittle injury, and good results of function recovery. It could be an effective and safe method in treating bilateral ANFH.