Isolated sphenoidal sinus disease is a rare form of paranasal sinusitis, accounting for about 3% of all paranasal sinus lesions. Infections such as viruses, bacteria, parasites, and fungi can all cause sinusitis. Isolated sphenoidal sinus disease is difficult to diagnose and treat because the symptoms are hazy and usually appear late due to disease complications. A 36-year-old woman presented to the ENT polyclinic 3 months ago with complaints of intermittent and worsening headache. The patient was treated for a headache at the neurological clinic and given analgesics, but the headache did not go away. The neurologist recommended a CT scan, which revealed a ridge in the right sphenoid sinus. The patient was referred to an otolaryngologist, who performed an endoscopic sphenoidotomy under general anaesthesia. The sphenoid ostium was dilated, and the headache was relieved postoperatively.