Introduction: One of the many causes of maxillary canine impaction is the mechanical obstruction by a small maxillary arch. By introducing Cone Beam Computed Tomography (CBCT) to the orthodontic field, studying such a relation became possible and accurate. Aim: The aim of this study was to compare the maxillary transverse dimensions between subjects with impacted maxillary canines and normal subjects using Cone Beam Computed Tomography. Methods: Cone-beam computed tomographic images of 60 adults were acquired. They were grouped into three groups of 20 each: buccal canine impaction, Palatal canine impaction and a control group. The width of the maxilla was measured skeletally, dentally and alveolar in each group using Dolphin software program. Results: the skeletal width of the maxilla was similar among study groups and control ones. It was found that there was a statistically significant difference between canine impaction groups and control group regarding the premolar width and the premolar alveolar width. As for the molar width and the molar alveolar width, there was no statistically significant difference between them. Conclusion: Premolar dental and alveolar widths of the maxillary arch were significantly smaller in palatal canine impaction subjects than in subjects with buccal impactions or normal subjects. Skeletal, molar dental and molar alveolar widths of maxilla had non-significant difference between canine impaction and normal subjects.