Mr. C, a 64-years-old male, suffered from left-side persistent headache for 3 days. He sought help at our outpatient department of Family Medicine because the pain disturbed his sleep. The initial impression in the clinic was cluster headache. However, brain computed tomography (CT) was arranged owing to two reasons. First, the headache first occurred after his 60's and he had no similar past history. Second, the pain was hardly controllable by acetaminophen. CT examination showed left-side subdural hematoma. He then received cranial surgery and hematoma drainage.Although the incidence of headache decreases with age, the incidence of secondary headache in the elderly is higher than in the general population. The leading causes of secondary headache in the elderly were polypharmacy followed by cerebrovascular accident, head injury and brain tumor. In addition to complete history taking, thorough physical and neurological examination, general practitioners should be cautious about clinical clues signaling secondary headache in an aim towards correct treatment.