Aspergillus infection of the paranasal sinuses is rare but is the most common fungal infection of these structures and should be suspected when sinusitis does not respond to antibacterial drugs. Our case involved the sphenoid sinus, and was initially thought to be a nonfunctioning pituitary tumor. Treatment of Aspergillus sinusitis principally involves surgical debridement, reestablishment of aeration and drainage of the involved sinuses, and adjunctive antifungal chemotherapy.