OBJECTIVE To investigate the ability of the biodegradable polycaprolactone (PCL) material to repair bone defect and to evaluate the feasibility of using the PCL as the scaffold in tissue engineering bone. METHODS The bone defect models of 4. 5 mm x 12 mm were made in the bilateral femoral condyle of 65 New Zealand white rabbits. The PCL cylinder was implanted into the right side of defect (experimental group, n = 60), the high dense hydroxyapatite was implanted into the left side of defect (control group, n = 60), and the incision was sutured without any implants (blank group, n = 5). The samples were harvested and observed by examinations of gross, X-ray, bone density, 99mTc-MDP bone scanning, gamma-display ratio and scanning electron microscope (SEM) after 3, 6, 9 and 12 months of operation. The results were compared between the experimental group and control group. RESULTS At 3, 6, 9 and 12 months after operation, the gross and X-ray examinations indicated that the bone defect filled with the new bone on the PCL-tissue surface, and no delayed inflammatory reaction appeared. The average bone mineral density was greater in the experimental group than that in the control group, and the difference had statistical significance (P< 0. 05). The results of 99mTc-MDP bone scanning and gamma-display ratio showed that the nuclide uptake was more in the PCL group than that in the control group. The SEM result proved that the new compact bone formed on the PCL migrating surface as the PCL degraded gradually,but the collagen fiber sheath formed around the hydroxyapatite in the control group. CONCLUSIONS PCL possesses good biocompatibility and high bone inductive potentiality, it can be used to repair bone defect.