Purpose: There are several vascular vessels that supply the maxillary sinus, such as the posterior superior alveolar artery, the anterior superior alveolar artery, and the infraorbital artery (IOA). These vessels have to be taken into consideration during a sinus augmentation because of the potential risk of bleeding during the procedure. The objective of this investigation was to study variations in maxillary sinus artery connections with the potential surgical effect during a sinus floor elevation by the lateral wall. Materials and Methods: The first part of the study was done in 32 anatomical specimens embedded in 10% formaldehyde solution and aged between 55 and 70 years (mean, 61.3 years). The second part of the study was a radiographic study using computerized tomographic (CT) scan images in 35 randomized patients treated in odontology and maxillofacial surgery departments. Results: Results were recorded for 134 sinuses. In most cases, there was no vessel visible or no vessel present with a diameter less than 0.5 mm after dissection or CT-scan analysis: 120 sinuses (89.5%). In 14 cases (10.5%) there were vessels in the lower two thirds of the anterolateral wall. In 10 sinuses (71.4% of the 14 cases), there was an intraosseous or intrawall artery and in 2 sinuses (14.3%) they were in the intrasinusal position. In 8 of the 14 sinuses (57.1%, about 6% of overall sinuses) the diameter was between 1 and 2.5 mm. Conclusion: Knowledge of the arterial supply is essential for surgical treatment in the sinus area. A CT scan is recommended and the radiologist must be advised to search for intraosseous or extraosseous vessels in the lower two thirds of the maxillary sinus. Keywords: maxillary sinus, sinus augmentation, vascular vessels