Introduction: Although experience with cavernous sinus (CS) surgery has increased over the years, it is still difficult to access the anteroinferior and lateral compartment with endoscopic endonasal transsphenoidal surgery (EETS) and resection rate of tumors which invaded the lateral compartment is low. This study aimed to determine whether the ETO approach could be an alternative and a safer route to access the CS lateral compartment. Materials and methods: ETO technique was studied on 3 cadavers and 6 CS of these cadavers. Endoscopic dissection was visualized with a 0-degree angle endoscope and recorded with fiberoptic cable, light source and camera system and digital video recording system. Results: Superior orbital fissure (SOF), optic canal (OC), anterior ethmoidal artery (AEA) and posterior ethmoidal artery (PEA) foramens were visualized with periorbital dissection. Anterior wall of CS was reached after drilling the optic strut (OS). When the wall was opened, CS lateral and anteroinferior compartments were visualized. Internal carotid artery (ICA) were visualized from proximal ring to the last 2 cm of paraclival carotid artery. Cranial nerves (CNs) within the CS and the course of the interclinoid ligament were revealed. Conclusion: The transorbital endoscopic method is an alternative approach to other techniques for accessing the lateral and anteroinferior compartments of CS. The advantages, disadvantages and limitations of the technique have been determined.