Objective To explore the effects of silk fiber and calcium phosphate cement (SF/CPC),a new composite material,on repairing bone defects in rabbits.Methods Models of bilateral radial bone defects were created in 48 New Zealand big-eared white rabbits which were subsequently divided into 4 even groups according to the materials used to fill the defects:group A where SF/CPC was used,group B where SF/CPC plus micromorselized bone was used,group C where micromorselized bone was used alone,and group D where nothing was used.The rabbits were raised in the same conditions after operation.Samples were harvested at 4 and 8 weeks postoperation for gross observation,X-ray,histopathologic and scanning electron microscopy examinations; biomechanical tests were also conducted at 4 and 8 weeks postoperation for statistical analyses.Results X-ray examinations found no repair but sclerosis of bone ends in group D while different extents of bone repair were observed in the other 3 groups.According to the X-ray,histopathological and scanning electron microscopy examinations,trabecular bone formation in group A was thinner than in groups B and C at 4 weeks.Bulky and mature trabecular bone formation was observed in all groups at 8 weeks.Biomechanical tests showed group A had a significantly weaker strength than groups B and C at 4 weeks (P ＜ 0.05),but there were no significant differences among groups A,B and C at 8 weeks (P ＞ 0.05).Conclusion The new composite material SF/CPC has a certain capability of repairing bone defects,because it possesses biocompatibility and osteoinductive ability,and similar strength of micromorselized bone composite as well.