Resumen: SUMMARY: The posterior superior alveolar artery is responsible for the vascularisation of the mucous which covers the posterior wall of the maxillary sinus, pulp and the periodontal tissues of upper molars. The collateral rami of the infraorbital artery irrigate the mucous of the anterior and lateral walls of the maxillary sinus, as well as the pulp and periodontal tissue of the upper anterior teeth and upper premolars. Both these arteries present intraosseous and extraosseous rami which form an anastomosis in the anterior and lateral walls of the maxillary sinus, called the alveolar antral artery (AAA). The aim of this study was to analyse the presence, location and morphometry of the AAA in a Chilean population, considering sex, side and age, using Cone-Beam computed tomography (CBCT). Forty-two CBCT examinations of Chilean adults were evaluated to analyse the presence, location (extraosseous, intraosseous or subperiosteal) and diameter (<1mm, 1-2 mm, 2-3 mm, >3 mm) of the AAA and the distance from the AAA to the amelocemental limit of the upper second premolar (2PM), permanent upper first molar (1M) and permanent upper second molar (2M) by sex and age range. Pearson's chi-squared test, Student's t-test, ANOVA and Pearson's correlation coefficient were applied, using a significance threshold of 5 %. AAA was found in 75 sides (89.3 %), 38 on the right side (90.5 %) and 37 on the left (88.09 %); extraosseous location was most common. More than 80 % of the arteries presented a diameter between 1 and 2 mm, with no important differences between sexes or age ranges. In younger individuals, the artery was located closer to the vestibular amelocemental limit than in older individuals. Carrying out a proper treatment plan which includes imagenological analysis before surgical procedures is essential to avoid possible haemorrhagic events in the region.