Headache at rest or on exertion could rarely be the only presenting symptom of an acute coronary syndrome. This is referred to as "cardiac cephalalgia". A healthy 37-year-old man presented with a headache of one week. He was initially treated with an analgesic and, a Magnetic Resonance Imaging of the brain was performed on day five of the illness as the headache was persistent. The next day he developed a generalised seizure, followed by unresponsiveness. He was rushed to hospital within 15 minutes and was pronounced dead on admission. Cause of death was established as acute myocardial infarction at post-mortem examination. This patient fulfilled the ICHD-3 diagnostic criteria for cardiac cephalalgia. Postulated mechanisms of cardiac cephalalgia include referred pain to cervical nerve roots, increased intracranial pressure from sudden reduction of cardiac output, cerebral vascular changes caused by chemical mediators released in myocardial ischaemia and hypoperfusion. Cardiac cephalalgia should be suspected in any unexplained headache, especially if the headache occurs in relation to exertion. Prompt diagnosis and treatment will reduce the morbidity and mortality in cardiac cephalalgia.