This study was done to determine the existence of any relation between bilateral agenesis of maxillary or mandibular third molar with antero-posterior dimension of maxilla, mandible and skeletal pattern. 82 initial records of Egyptian patients with bilateral congenitally missing third molars, either in maxilla / mandible were selected. The records were divided into four groups 1- bilateral missing of upper third molars, 2-bilateral missing of lower third molars, 3- bilateral missing of upper and lower third molars, 4- control group without missing. Molars Orthopantomographs were used to determine the presence or absence of third molars. Lateral cephalometeric radiographs used to carry out a cephalometric analysis including linear, angular and proportional measurements. After collecting the data, it was analyzed by means of Anova and Tukey tests.The results obtained that mandibular plane angle were reduced, but not statistically significant. Whereas values of gonial angle in group III were significantly lesser than the control group (P =.006). For group III facial height was significantly less than the control group (P=.030).The conclusion suggests that agenesis of upper and lower third molars related to a reduced gonial angle, and decreased facial height. The study showed a relation between third molars agenesis and facial morphology.