Objective To explore an ideal operative treatment to preserve the hi p joint for the old femoral neck fracture in young and middle-aged patients. Methods Between January 2002 and June 2006, 28 cases of old femoral neck fracture, 23 males and 5 females, aged 19-55 years old (37.6 on average), were reconstructed with free il iac grafts and fixed by dynamic hi p screws (DHS) and/or canulated screws. Multi ple vascular bundles derived from lateral circumflex femoral vascular were implanted in 19 cases. All the 28 cases were close fractures, with 17 of left hip and 11 of right hip. In terms of the fracture site, 4 cases were infer-head, 17 were per-neck and 7 were fundamental-form. The Harris score was 25-72 (49.6 onaverage) before operation. No callus formation was found on X-ray films in all cases; sclerosis and cyst were found in 4 cases and osteonecrosis of femoral head (ONFH) was confirmed by MRI. The duration between initial injury and surgery was 1-21 months (8.6 months on average). Results No deep infection was observed in all 28 cases, and paralysis of the lateral cutaneous nerve of the thigh was observed in 5 cases, and was better 6 months after operation with no special treatment. All 28 cases were followed up for 20-72 months (35.8 months on average). A total of 25 fractures healed within 4-8 months, with the heal ing rate of 89.3%; 3 fractures had nonunion and received artificial hip replacement. During the follow-up, 7 cases (25%) developed ONFH confirmed by MRI within 18 months, and 5 cases (17.9%) developed femoral head collapse. The Harris score was 27-100 (82.7 on average). Leg length discrepancy was not observed and the gait was fairly normal. Conclusion The femoral neck reconstruction procedure can restore the normal anatomy of femoral head and neck and the blood supply, so as to promote fracture heal ing as well as delay or avoid the artificial joint replacement. Therefore, it is an important treatment to preserve the hip joint for the old femoral neck fracture in young and middle-aged patients.