The aim of this study was analyze the positioning of the mandibular foramen in men and women, relating it to the inferior alveolar nerve block. Were analyzed CBCT scans of the mandible of 25 women and 25 men, aged between 20 and 40 years, with toothed jaws, presence of the second molar erupted and in occlusion. To determine the position of the mandibular foramen, three measurements were taken in millimeters, Point A - distance from the foramen to the anterior border of the mandible; Point B - distance between the foramen to the base of the mandible and Point C - distance between the foramen and the mandibular notch. The mean measure point A was 11.8 mm and when compared the points A, B and C between the right and left sides, there was no significant difference, however men and women have significant differences were detected for point B and point C. Conclude that in men and women, can use needles with at least 21mm in length with the insertion in the level of occlusal plane for blocking the inferior alveolar nerve, enhancing the success of this procedure.