Introduction: Cholecalciferol (Vitamin D3) is essential for bone mineralization and for the subsequent maintenance of bone quality. Supplementation with Cholecalciferol (vitamin D3) is reported to show positive effects on bone mineral density Objectives: Evaluation of the effect of Cholecalciferol on dental implant osseointegration. Materials and Methods: The study was conducted on fourteen adult male mongrel dogs.Dogs were divided equally into two groups, control group and study group, seven dogs in each group. Extraction of mandibular right premolar and insertion of immediate titanium implant had been done for all dogs in both groups, and then only the dogs of the study group received Cholecalciferol for four weeks. Histological and radiographical evaluations were carried out after twelve weeks postoperatively for both groups. Results: Histological results revealed improved bone healing in the study group, as shown by marked osteoblastic activity and accelerated woven bone formation, and absence of chronic inflammatory cells. The highest rate of bone ingrowth occurred in the study group. Radiograghical evaluation revealed that the peri-implant bone density had increased significantly in the study group. Conclusion: These results indicated that Cholecalciferol vitamin D3 has systemic effects on accelerating bone formation around titanium implant