Objectives: Study of sphenoid sinus anatomy and neurovascular structures adjacent by using CT scan to apply in endoscopic skull base surgery. Patients and methods: This is prospective study based on CT scan of sphenoid sinus in 45 patients. Results: The post sellar type of sphenoid sinus was found in 88.89 percent, presellar type in 6.67 percent and conchal type in 5.6 percent. The sphenoid sinus have two septum in 51.1 percent, 1 septum in 28.8 percent, 3 septum in 13.3 percent and more than 3 septum in 6.8 percent. Sphenoid septum insert directly in to the bony covering of the carotid artery in 22.3 percent. The protrusion of carotid artery was found in 31 percent and the exposed carotid artery in 8.8 percent. The protrusion of optic nerve was found in 6.6 percent. Conclusions: Study of sphenoid sinus anatomy and neurovascular structures adjacent on CT scan is needed to help indication the approach and reduce complications in endoscopic skull base surgery.