SUMMARY:The purpose of this study was to compare dental arch transversal and anteroposterior dimensions in three ethnic groups from Colombia. A digital caliper was used to take 16 transversal and two sagittal measurements, 9 for the upper jaw and 9 for the lower jaw. The sagittal measure determining arch length was drawn from a mesial line traced from first right permanent molar to first left permanent molar, and a perpendicular line from the point of contact between central incisive teeth, both for the upper and lower jaw. The dimensions of upper dental arch in the three ethnic groups showed differences in intercanine distance, as well as between premolar and between molar teeth. The same differences were found for lower dental arches. The populations evaluated show distinctive characteristics in dental arch dimensions, thus the mestizo population had narrow arches while the natives had wide arches.