The purpose of this study was to investigate maxillary and mandibular transverse skeletal and dental width in untreated subjects with low, average, and high mandibular plane angles. Methods: sixty untreated male and female children with low (≤ 23°, n = 20), average (> 23° to < 29°, n = 20), and high (≥30°, n = 20) mandibular plane angles were selected. For each subject dental casts, lateral and posteroanterior cephalometric x-rays were taken and the widths of maxilla and mandible, the intermolar and intercanine widths were measured. Results; No significant differences were found in the dental nor skeletal widths between the three tested groups neither in males nor in females.