Objective To retrospectively analyze the cl inical effect of l ightbulb operation with nano-hydroxyapatite/ collagen in a consecutive series of patients with osteonecrosis of the femoral head (ONFH). Methods From January 2001to July 2005, 26 patients (35 hips) were treated, 16 males and 10 females, aged 19-54 years old (33.5 on average). The course of disease was 12-36 months (18 months on average). Based on the etiology, 15 cases (22 hips) were steroid induced type, 10 (12 hips) were alcohol induced type and the other one (1 hip ) was idiopathic type. According to the system of Association Research Circulation Osseous (ARCO), there were 6 hi ps of stage IIB, 16 hi ps of stage IIC, 9 hi ps of stage IIIA, 3 hi ps of stage IIIB and 1 hip of stage IIIC. The Harris score was 62.2 ± 7.5. All the patients who had undergone l ightbulb operation with nano-hydroxyapatite/collagen were evaluated both cl inically and radiographically. The bone graft mixture rate of nanohydroxyapatite/ collagen and autogenous bone was 1 ∶ 1, and the mixed bone graft was 6 times of the scraped osteonecrosis volume (30-48 mL). Results The incisions of all 26 patients (35 hi ps) obtained heal ing by first intention. The 2 cases, which got lateral femoral cutaneous nerve injury during the operation, recovered 3-6 months after the operation without any treatment. Another 2 cases got heterotopic ossification 3 months after operation, with no special treatment. All the 26 patients (35 hips) were followed up for 2-7 years (3.5 on average). The patients’ bone heal ing began from the 3rd month after operation. The postoperative Harris score was 85.1 ± 16.2, and there was significant difference compared with the preoperative one (P lt; 0.001). There were 15 hips of excellent, 11 of good, 5 of fair, and 4 of poor which received total hip arthroplasty at the end of the follow-up. According to imaging, 5 hips were progressed from preoperative IIC to IIIA, while the other hips were radiologically stable, with no progress of ONFH. Conclusion Lightbulb operation with nano-hydroxyapatite/collagen provides a surgical treatment to treat early ONFH with satisfactory cl inical outcomes. Nano-hydroxyapatite/collagen is beneficial for the repair and reconstruction of ONFH and suitable for femoral-head-preserving operation for the patients with ONFH of stage II.