Introduction: The purpose of this study was to assess the thicknesses of maxillary and mandibular posterior buccal approximal attached gingiva at common miniscrew insertion sites, which has critical importance in deter- mining miniscrew length, in subjects with different facial types. Methods: One hundred seventy-four subjects with no transversal skeletal discrepancy were included in this study. The facial types of these subjects were evaluated in the sagittal and vertical directions. In the sagittal direction, the subjects were assigned into 3 groups: skeletal Class I, II, and III. Also, each of these groups was divided into subgroups in the vertical direction: low angle, norm, and high angle. Transgingival probing was used to measure the thickness of the buccal attached gingiva. Results: The thickness of the buccal attached gingiva between the second premolar-first molar ranged from 1.18 +/- 0.33 to 1.46 +/- 0.28 mm and from 1.28 +/- 0.30 to 1.58 +/- 0.37 mm in the maxilla and mandible, respectively. The thickness of the buccal attached gingiva between the first-second molars ranged from 1.31 +/- 0.41 to 1.60 +/- 0.62 mm and from 1.36 +/- 0.43 to 1.72 +/- 0.52 mm in the maxilla and mandible, respectively. In terms of the thicknesses of the buccal attached gingiva of second premolar-first molar and first-second molars, no statistically significant difference was found between subjects with different facial types. Conclusions: It was determined that the thicknesses of maxillary and mandibular posterior buccal approximal attached gingiva varied between 1.18-1.72. At this point, the insertion of miniscrews of 7-8 mm in length was recommended for maxillary and mandibular posterior buccal regions, in order to obtain adequate insertion depth.