Autologous bone grafts are used to reconstruct mandibular bone defects because autologous bone is highly osteogenic and does not elicit immune reactions. Because harvesting these grafts requires an additional invasive surgical procedure, we attempted to construct bone grafts from decellularized xenogeneic bone. Fragments of porcine femur cortical bone were assembled into pairs and fastened together using suture thread. They were pressurized hydrostatically to disrupt cells, washed to remove all the cell debris, and implanted subcutaneously in rats. After implantation, few immune reactions were observed and the bone fragments were not absorbed. Cells in the gap between fragments were observed histologically one week after implantation. Two weeks and four weeks after implantation, the gap was not discernible on X-ray micro CT images, and a bone-like collagen matrix was observed in the gap histologically. These findings suggest that the assembled decellularized bone fragments induce formation of bone matrix to fill the gap. Decellularized bone has the potential to be an alternative material for bone graft.