The effects of ketorolac on bone repair were studied radiographically. The effects of methylprednisolone were also compared. Demineralized bone matrix was grafted into the fractured gap of rabbit’s ulna as an experimental bone repair model. The rabbits received ketorolac 2 or 4 mg/kg body weight daily for 6 weeks after transplantation. Serial radiographic studies were performed 2, 4, and 6 weeks after transplantation. Mineralization of grafts and bone union were evaluated as the parameters of bone repair. Comparing the bone repair among groups at individual time points, ketorolac-treated groups showed no statistical differences as compared with the control group in either mineralization or bone union, whereas methylprednisolone significantly suppressed both parameters. However, comparing the mineralization during the healing process in each group, the control group and the group treated with ketorolac 2 mg/kg showed a significant increase during the period from the 2nd to the 4th week of medication, whereas both the group treated with ketorolac 4 mg/kg and the methylprednisolone-treated group showed no significant increase during this period. This poor mineralization of grafted bone in repair process affected by ketorolac suggests that 4 mg/kg of ketorolac might delay the endochondral ossification process during the period from the 2nd to the 4th week of fracture healing.