Objective: This doctoral thesis is a retrospective-prospective anatomic-radiologic study with an objective to research anatomic variations of sphenoid sinus shown by computed tomography. ----- Patients and methods: The study included 122 subjects, 58 men and 64 women. All patients underwent computed tomography examination during the usual procedures for suspected paranasal sinus diseases. The aim was to investigate the spreading of the sphenoid sinus extensions into the parts of the sphenoid bone; the anterior clinoid process; the greater wing and into the pterigoid process of sphenoid bone, as the protrusion of the optic nerve, maxillary nerve and the vidian nerve into the sphenoid sinus. Dehiscence bony partitions that can be found between nerve structures and sphenoid sinus were also researched. ----- Results: ACP pneumatization, GWS and the PP was found in 39 (31.97%), 48 (33.34%) and 62 (50.82%) patients respectively. VN protrusion, MN and ON was found in 61 (50%), 44 (56.07%) and 33 (27.05%) patients respectively and dehiscence bone septum between these neural structures and sphenoid sinus in 54 (44.26%) , 29 (23.77%) and 24 (19.67%) patients respectively. ----- Conclusion: Sphenoid sinus is highly variable. Anatomic variations of sphenoid sinus are common. Computed tomography, especially, MSCT in particular is the method of choice in the detection of anatomic variations of sphenoid sinus and is increasingly becoming the gold standard for evaluating planned preoperational endonasal, endovascular procedures on the sinuses, as also before neuro microsurgery on structures that surround the sinus, especially on the Sella turcica transsphenoid approach for removal of pituitary adenomas.