Longitudinal differences on the left and right sides of the jaw with respect to the midline in three spatial planes are called mandibular asymmetries. Objective: To determine the frequency of mandibular asymmetries in three spatial planes by means of Cone Beam computed tomography (CBCT) and classify them according to the degree of difference between both sides. Methods: A total of 40 Cone Beam volumetric tomography (New Tom 3G Cone Beam Volumetric tomographic scanner) records were analyzed using simple random sampling of patients between the ages of 18 and 70 from 2011 until 2013. Axial slices were obtained from the lingula in cranio-caudal direction every 5 mm until the gonial angle. Results: From the records, 2.5% showed moderate degree of difference in the length of the mandibular body with predominance on the right side. For breadth of the ramus, predominance was found on the left side. In the length of the mandibular ramus, 10% presented moderate degree of predominance on the right side. Conclusions: 1) asymmetries are more frequent at the level of the mandibular ramus thickness; (2) moderate and severe degrees of differences are most frequently found in the mandibular ramus thickness. 3) It is not possible to proportionally determine mandibular ramus thickness only with a 2D image