In some forms of cerebrovascular disease, such as intracranial hemorrhage, headaches are well known as a prominent symptom and often are a valuable clue to diagnosis. There are difficulties, sometimes, in distinguishing between a small subarachnoid hemorrhage and a severe migraine headache, but these can be resolved using clinical observations, CT scan, and lumbar puncture. It seems less well known that headaches may accompany or precede cerebral thrombosis and embolism. When these headaches are recognized as a forerunner to stroke, they may allow an opportunity for preventive treatment.