Several life-threatening complications caused by hemorrhage that can occur during the placement of dental implants in the mandibular interforaminal region have been described in the literature. The aim of this study was to assess the vascular supply to this region and delineate the relative contribution and importance of the sublingual artery versus the submental artery. Thirty-four human cadavers were dissected. Special attention was directed to the presence of a branch of the submental artery that perforates the mylohyoid muscle and thus participates in the blood supply to the floor of the mouth together with the sublingual artery. A sublingual artery was found in 71% of the specimens. A large branch of the submental artery perforating the mylohyoid muscle was found in 41% of the specimens. The point of perforation was located an average of 31 mm posterior to the menton. The high risk of injuring the vessels of the floor of the mouth can be explained by the close vicinity of these vessels to the mandibular lingual cortical plate. To prevent complications in cases of unclear anatomic identification of the fossa sublingualis, preoperative lingual probing or elevation of the periosteum of the lingual aspect of the mandible is necessary. An alternative diagnostic procedure is precise preoperative noninvasive imaging (eg, computed tomography). Keywords: endosseous implants, floor of the mouth, hemorrhage, vessels