Objective: The aim of this study was to evaluate the effect of some morphological features of the mandible and mandibular permanent molars on impaction of mandibular third molars with panoramic measurements in a Turkish patient group. Study design: Standardized panoramic radiography variables compiled from 140 patients retrospectively were eva- luated. Predictive variables included mesio-distal crown width and inclination of the mandibular molars, vertical and horizontal surface dimension between distal surface of the lower second molar tooth and anterior surface of its ramus, length and width of the mandible ramus and corpus, angle of the mandible gonion, the number of the lower third molar roots, and angulations of roots of the lower third molars. Results and Conclusions: According to the data obtained in this study, the vertical height of the anterior border of the ramus, length of the posterior basal corpus, mesio-distal diameters of the first, second and the third molars, 1/3 root angle of the third molar, number of third molar roots, inclination of the first molar to increase, vertical height of the posterior border of the ramus, vertical height of alveolar crest, and height and the width of the retro-molar space to decrease are all in direct proportion to the possibility of impaction of the third molar.