Background: Nano could promote strong biological bonding between implants. In this study the effect of cancellous bone scaffold coated with/without Nano-hydroxyapatite in vivo using an animal model of bone healing was studied. Methods: In an experimental study, 18 adult male New Zealand white rabbits were used dividing into three groups of six rabbits each. A segmental bone defect of 10 mm in length was created in the middle of the right radial shaft under general effective anesthesia in all rabbits. The defects in group I were left as such without filler, in group II the defect were filled up with harvested 10 mm rib bone and in group III the defect were packed with rib bone covered with nano-hydroxyapatite. The operated radiuses were removed on the 60th day and were pathologically and biomechanically evaluated. Results: The radiographs showed a trace of internal callus filled the gap in 60 days in group I, whereas in group II and III internal callus almost was formed on 30 days. Repair defect in group I and II with group III and load bearing of group II, III compared with group I showed no significant difference (p < /em>