Aim: The conventional radiographic examinations are two-dimensional representations of three-dimensional objects. These techniques become insufficient in the diagnosis, treatment planning and orthodontic prognosis, especially in orthognathic surgery cases. The aim of this study is to analyse the effectiveness of cone beam computed tomography (CBCT) in the evaluation of the position, angulation and displacement of the condyles, before and after orthognathic surgery. Materials and Methods: We evaluated the condylar changes in 20 patients from the department of orthodontics of Faculty of Medicine (University of Coimbra), undergoing orthognathic surgery between December 2013 and April 2016. The angulation, condylar position and intercondylar distance were measured by CBCT before and after the surgery. Results / Discussion: There were no statistically significant differences between the values of the angulation and position of the condyles as well as of the intercondylar distance in pre and post-surgical phases. Analysing the average values, there was an increase of the axial angle of the left condyle and the frontal angle of both condyles, while there was a decrease of the axial angle of the right condyle, the sagittal angle of both condyles and intercondylar distance. Conclusion: The CBCT is a useful method for assessing variations of condylar position in pre and post-surgical phases. It was found that, after the surgery, the condyles tend to do a postero-inferior movement. Furthermore, long-term studies with larger sample sizes are needed to ascertain an eventual recovery of the original condylar position and the maintenance of post-surgical stability. Keywords: CBCT, orthognathic surgery, condylar position, condylar assessment