Objectives: To measure frontal bone thickness in skeletal hyperdivergent and hypodivergent patients and compare with a group of normodivergent patients. Settings and sample population: The material comprised of 150 patients divided into three group, 50 patients with skeletal hyperdivergence and 50 with skeletal hypodivergence. They were compared with a control group of 50 patients of skeletal normodivergence. Materials and methods: The thickness of the frontal bone was measured on lateral radiographs of patients with skeletal hyperdivergence and skeletal hypodivergence and compared with a control group. Unpaired t- test were used for evaluating differences in thickness. Results: Patients with skeletal hyperdivergence had a significantly thicker frontal bone than a normodivergent group. Frontal bone thickness in skeletal hypodivergent patients was comparable to the normodivergent group. Conclusion: The most important outcome of this study was increased thickening of frontal bone in patients with skeletal hyperdivergence compared with skeletal normodivergent patients. Deviations in the theca cranii are thus associated with skeletal hyperdivergence.