Although the sphenoid sinuses can be identified in sections of the fetus at 4 months, at birth the sinus remains small and is little more than an evagination of the sphenoethmoid recess. After the 3rd year, invasion of the sphenoid bone is more rapid, and by the age of 7, the sinus has extended posteriorly to the level of the sella turcica. By the age of 12, the sphenoid pneumatization reaches its final form and a size equivalent to the adult, although further enlargement into the basisphenoid may occur in the adult. Agenesis of paranasal sinuses is an uncommon clinical sign and refers mainly to the frontal and secondarily to the maxillary sinuses. Agenesis of sphenoid sinuses is a very rare phenomenon in the literature. We present a 32-year-old male patient with agenesis of sphenoid sinuses that was studied by CT.