The aim of the study was to : Prediction of the combined mesiodistal widths of the permanent mandibular incisors and maxillary and mandibular canines and premolars in a group of Egyptian children in Al Mansoura Governorate. Correlate between the combined mesiodistal widths of the teeth under study . Subjects and Methods : This study conducted to measure the mesiodistal width of mandibular incisors and maxillary and mandibular canines and premolars of three hundred patients with an age range from eleven to fifteen years attending schools of Al Mansoura City. Results: The results of this study revealed: No statistically significant difference in the mean mesiodistal tooth width between right and left sides in all teeth under study. Boys showed larger mesiodistal tooth width than girls. Positive correlation between the sum of the mesiodistal width of (upper right canine and premolars) & the sum of the mesiodistal width of the lower incisors.