Headache represents up to 4% of all emergency department (ED) visits. Emergency physicians generally are concerned with identifying those patients whose headaches are caused by life-threatening conditions. Cerebral venous sinus thrombosis may be difficult to diagnose clinically because of its various and nonspecific manifestations. The most frequent but least specific symptom of sinus thrombosis is severe headache, which is present in more than 90% of adult patients. In the case report we present, a patient had severe headache and was diagnosed until third ED visit at different hospitals. He had one of the most unusual causes of headache, that is, cerebral venous sinus thrombosis due to hyperthyroidism.