The anterior ethmoid artery (AEA) is an important structure in functional endoscopic sinus surgery1) and is regarded as a key landmark for surgical approaches to important anatomical structures, such as the frontal sinus and the anterior skull base. 2, 3) In its course through the ethmoid cavity, the position and the course of the vessel is variable, therefore, classified into three subtypes: through the anterior part of the skull base bone, just inferior to the skull base, or away from the skull base in the ethmoid cavity. 4, 5) For this reason, before performing surgery, surgeons must recognize these structural differences and relationships with surrounding structures, such as the skull base, frontal sinus, and orbit. 1) The frontal sinus is the most challenging sinus for the endoscopic sinus surgeon due to its anatomical complexity and variability; 6, 7) there are many studies reporting anatomical landmarks that may assist the surgeon in making a safe approach to the frontal sinus. 7-9) The AEA is known as a typical and classic landmark of the frontal sinus and there are several studies re-