Purpose of the study : This study aimed to determine the height at which both the lateral and medial cortical bone layers of mandibular ramus merge, using a reference point on the anterior margin of the mandibular ramus and comparing with lingula as another reference point, using cone beam computed tomography, thus establishing an effective method of determining the level of the horizontal cut of sagittal split osteotomy. Material and Methods: The mandibular ramus of 15 patients were analysed on a three dimensional (3D) model constructed using Cone Beam Computed Tomography. Starting at reference point (A), a line was marked from the anterior border of the ramus of mandible till the posterior border on lateral surface. On three vertical section of the ramus (1/3rd and 2/3rd and lingula), the level at which both lingual and buccal cortices meet were determined- A1 and A2 and L respectively. The results of the study showed that mean height of fusion of medial and lateral cortices at 1/3rd and 2/3rd and lingula were 8.96mm, 4.62mm and 11.00mm respectively. Conclusion:The point A is a safe and easy to locate anatomic reference point to establish the level of horizontal cut in sagittal split ramus osteotomy (SSRO).