Objective   To investigate the osteoinductive effect of insulin-like growth factor-Ⅰ(IGF-Ⅰ) in tissue engineered bone complex of hydroxyapatite (HA)/autogenous red bone marrow (ABM).    Methods   The animal model of bone defect of one thirds bilateral radius was made on 36 rabbits. The animals were randomly divided into 4 groups. Their defects were repaired with no implant for the blank control group

with HA/ABM implant for HA/ABM group

with implant 400 ng/ml IGF-Ⅰ pre-added HA for IGF-Ⅰ/HA group， and with IGF-Ⅰ/ HA/ABM implant for IGF-Ⅰ/HA/ABM group. Gross observation

X-ray examination and scanning electronic microscopy were used to study the repair of defect before and in 1

2

4

8 and 12 weeks after the repairing. Serum level of alkaline phosphatase (ALP) was detected.    Results   Serum level of ALP was significantly higher in IGF-Ⅰ/HA/ABM group than in other groups in 2

4

8 and 12 weeks after repairing (P0.05)

and the difference of serum ALP had statistical significance among these groups (P0.05). Scanning electronic microscopy showed that there was a few amount of complex in the defect of IGF-Ⅰ/HA/ABM group in 12 weeks

and the defect was filled by mature lamellar bone which having no distinguished difference with normal bone. Better repairing was seen in IGF-Ⅰ/HA/ABM group than in other groups.    Conclusion   IGF-Ⅰ exerts significantly osteoinductive effect on tissue engineering bone of HA as scaffold material.