Background. Using one-stage bilateral free vascularized fibular grafting (FVFG) to treat avascular necrosis of the femoral head (ANFH) remains controversy due to potential high-risk and technical complexity. The purpose of the present study was to evaluate the safety and effectiveness of one-stage bilateral FVFG procedure versus unilateral FVFG in the treatment of ANFH. Methods. One-stage bilateral FVFG was performed for 26 patients with bilateral ANFH between March 2001 and September 2006. The clinical and radiographic outcomes, hospital stays, and postoperative complications in this group were compared with those from another 33 patients (40 hips) receiving unilateral FVFG. Results. The two groups had similar hospital stays, clinical outcome, and few complications. In an average follow-up of 36 months, one major and five minor complications were encountered in the onestage bilateral group, and one major and three minor complications in the unilateral group. The mean Harris hip scores increased from 63.8±16.795%CI: 61.266.4 to 84.2±1795% CI: 81.586.9 points in the unilateral group and from 61.7±22.295%CI: 58.664.8 to 82.0±16.6 95%CI:79.784.3 points in the one-stage bilateral group. In radiographic, there was no obvious difference in progression of collapse between the two groups. Conversion to hip arthroplasty was performed in 2 (5%) hips in the unilateral group and none in the one-stage bilateral group, with no statistically significant difference between the two groups. Conclusion. Using one-stage bilateral FVFG to treat ANFH is a safe and effective method with minor postoperative morbidity