The authors experienced a patient of fibrous dysplasia originating from the ethmoid bone which presented with severe headache with some features suggestive of menstrual migraine without aura. Fibrous dysplasia originating from the ethmoid bone is a rare disease entity, but may cause severe headache that can be misdiagnosed as "menstrual migraine" because of similar symptoms in female patients. Because the primary objective of surgery is symptomatic relief, conservative transnasal endoscopic approach may be considered an alternative to more invasive external surgical techniques in carefully selected patients, especially originating from the nasal cavity and paranasal sinuses.