Bone grafts are widely used in the reconstruction of osseous defects in the oral and maxillofacial region. Autogenous bone grafts are considered the gold standard in grafting of the oral and maxillofacial region, because of its osteoconductive and osteoinductive properties. Mandibular symphysis & ascending ramus bone graft have been used more frequently because of easy surgical access, reduced operative time, and following minimal morbidity. However, even though the frequent use of the anterior part of ascending ramus and the different regions of mandible, rare of the reports provide information about the quantity of bone available in this donor site. So this study was taken to evaluate & quantify the amount of bone graft material in the anterior ascending ramus regions. This study was made on 36 samples of CT image. In 3D volume image, imaginary osteotomy & segmentation were done and the dimensions and volume of the bone grafts were measured and evaluated. the average volume of the graft materials obtained from the ascending ramus was $3656.83{pm}108.19mm^3$, and the average dimensions of graft materials were $(33.68{pm}0.48){ imes}(34.92{pm}0.51){ imes}(15.96{pm}0.27){ imes}(9.05{pm}0.27)mm$.