The diagnostic approach to facial asymmetries is classically based, in addition to the clinical examination, on a cephalometric analysis carried out on a frontal radiography. Planning of orthognathic surgery requires a three-dimensional (3D) examination to visualize deformities. Nevertheless, the use of cephalometric analysis on 3D imaging remains clinically modest. The main objective of this study was to compare the cephalometric measures obtained from frontal radiographies and 3D imaging in patients with facial asymmetries.Frontal radiographies and 3D CT scans used for orthognathic surgery planning of 24 patients with asymmetries were selected. Cephalometric points were manually placed on 2D and 3D images by an operator, twice at a 4-week interval. The asymmetry of the subjects was quantified from 12 measurements, then the data obtained in 2D and 3D was compared. Intra-examination repeatability has been calculated.2D-3D average differences above 2 mm were found in the quantification of mandibular, jugal and maxillary molar symmetry and in the measurements of mandibular symmetry. The 3D measures showed a better repeatability than the 2D measures.The 2D-3D variations observed could have a clinical impact in the diagnosis and management of patients with facial asymmetries. Other studies remain necessary to provide more clinical evidence of the benefits of 3D cephalometry.