Objective To study the effect of combined use of autologous micromorselized bone with bone morphogenetic protein(BMP) and type Ⅰ collagen graft on the treatment of segmental bone defects. Methods The bulk bone of rabbit iliac crest was ground into micromorselized bone, which was combined with BMP and type Ⅰ collagen. The model of 1.5 cm bone defect was established in the middle shaft of the radius. Fifty-six rabbits were assigned to four repairing methods: autologous micromorselized bone graft with BMP and type Ⅰ collagen, autologous micromorselized bone graft with type Ⅰ collagen, autologous micromorselized bone graft alone, and control group. The defect-repairing capability of each group was assessed by radiographic, histological, bone densitometry and biomechanical studies. Results X-ray manifested that at the end of 8 weeks after operation, the bone defect treated with autologous micromorselized bone graft with BMP and type Ⅰ collagen was repaired completely,and at the end of 12 weeks after operation the bone defect treated with autologous micromorselized bone and type Ⅰ collagen was cured completely, but the bonedefect treated with autologous micromorselized alone was completely repaired. No healing was found in the control group. In the bone densitometry detection, the material with BMP exhibited the best defectrepairing capability in terms of amount increased and quality of the new bone at the end of 8 weeksand 12 weeks. The group with BMP has the best mechanical strength of all groupsat the end of 12 weeks. Conclusion Autologous micromorselized bone graft with BMP/type Ⅰ collagen and autologous micromorselized bone graft with type Ⅰ collagen prove to be effective in repairing segmental bone defects. The autologousmicromorselized bone combined BMP and typeⅠcollagen is an excellent bone repairing material considering the satisfactory osteogenesis, osteoconduction, and osteoinduction seen in this method.