Objective To investigate the effectiveness of transplanting iliac bone flap with deep iliac circumflex vessels and cancellous bone for the treatment of adult avascular necrosis of the femoral head (ANFH). Methods A retrospective analysis was made on the clinical data of 685 patients (803 hips) with ANFH, who underwent iliac bone flap transplantation with deep iliac circumflex vessels and cancellous bone between March 2002 and January 2010. There were 489 males (580 hips) and 196 females (223 hips) with a mean age of 40.4 years (range, 18-63 years), including 567 unilateral cases (303 left hips and 264 right hips) and 118 bilateral cases. The causes of ANFH included alcohol-induced in 223 cases, steroid-induced in 179 cases, alcohol + steroid-induced in 21 cases, traumatic in 136 cases, acetabular dysplasia in 8 cases, bone cyst in 5 cases, septic arthritis in 2 cases, joint tuberculosis in 3 cases, rheumatoid arthritis in 5 cases, and idiopathic in 103 cases. According to Steinberg staging, 211 hips were rated as stage II, 513 hips as stage III, and 79 hips as stage IV. The preoperative Harris hip score was 60.30 ± 7.02. Results Fat necrosis occurred in 2 cases after operation, primary healing of incision was obtained in the other cases; delayed infection, lower extremity deep vein thrombosis, and pulmonary embolism occurred in 2 cases, respectively. All patients were followed up 36-60 months (mean, 49 months). Harris hip score at last follow-up (83.50 ± 7.31) was significantly higher than that at preoperation (t= — 2 266.980, P=0.000), and the scores were significantly higher than those at preoperation in different stages (P lt; 0.05). The results were excellent in 523 hips, good in 185 hips, fair in 65 hips, and poor in 30 hips, and the excellent and good rate was 88.2%. X-ray examination showed bone fusion of transplanted bone flap and bone graft with an average of 4.2 months (range, 3-6 months); according to Steinberg staging, imaging stable rate was 78.3% (629/803) at last follow-up. Conclusion Iliac bone flap transplantion with deep iliac circumflex vessels and cancellous bone has the advantages of complete decompression of the femoral head, exact flap blood supply, improved blood supply of the femoral head, new support for the femoral head, and participation of osteoinductive effect for the treatment of adult ANFH, so it is an effective treatment for the retention of the femoral head.