Objective To investigate the effect of insulin-like growth factor-1(IGF-1 ) on the osteogenic phenotype of fibroblasts. Methods Fibroblasts (Fbs) were derived from an adult New Zealand white rabbit through isolation,purification and cultivation.The experiment was conducted in 3 groups.In the control group,Fbs were cultured in conventional medium without any intervention factors.In the osteogenic induction group,the osteogenic induction medium was composed of conventional medium plus dexamethasone at concentration of 1 × 10-8 mol/L plus vitamin C at 50 mg/L plus sodium glycerophosphate-β at 10 mmol/L.In the experimental group,Fbs were cultured in osteogenic induction medium plus IGF-1 at the final concentration of50 ng/mL.Proliferation of Fbs in each group was detected by methyl thiazolyl tetrazolium (MTT)colorimetric assay.Alkaline phosphatase(ALP) activiiy was detected,osteocalcin 6 days after culture was determined,and the ability of osteogenic differentiation 2 weeks after culture was evaluated by calcium-cobalt staining. Results MTT showed that the cells grew significantly faster in the experimental group than in the other 2 groups( P ＜ 0.05),but there was no significant difference between the control group and the osteogenic induction group in this respect (P ＞ 0.05).The ALP expression in the experimental group was insignificantly higher than in the osteogenic induction group( P ＜ 0.05),but significantly higher than in the control group ( P ＜ 0.05).In osteocalcin secretory activity,the experimental group was significantly superior to the other 2 groups and the osteogenic induction group was significantly superior to the control group ( P ＜0.05).The experimental group had significantly more calcified nodules than the other 2 groups and there were few calcified nodules in the control group 2 weeks after culture. Conclusion IGF-1 can advance proliferation and osteogenic phenotype expression of the Fb stimulated.