The mental foramen (MF) guides the mental nerve which is responsible for the sensible innervation of the mandibular area. It is important to know the anatomical variations of the MF for locational blockage of the incisor nerve in periapical surgeries involving molars and premolars, and in other buccomaxillofacial surgical procedures as well. This study aims to analyze variations in the MF site in dry mandibles of adult subjects in Southern Brazil. Eighty mandibles were analyzed, and the measurements of the distance from the sagittal midline to the center of the MF (MLF); the distance from the lower rim of the mandible to the center of the MF (LRF); the location of the MF relative to its alignment with the mandible teeth, and the incidence of double mental foramens (DMF) were checked. The analyzed parameters were related to each mandible’s laterality. Statistical analysis was carried out through Student’s t test. Results indicate that the prevalent position of the MF in the right and left sides was posterior to the first premolar. There was no significant difference between the right and left sides regarding MLF, and LRF showed a significant difference between sides, greater on the right side. There was a prevalence of the DMF on the right side of the mandibles. These results are important for the preparation and conduction of surgical procedures in order to prevent injury to the involved neurovascular structures.