We report three cases of thyrotoxicosis who presented acutely with headache to our neurology service in a 1-year period. In two of these patients there was a pre-existing or subsequent history of migraine. With hindsight, there were other clinical features of thyrotoxicosis but this diagnosis had been missed in primary care. Severe headache can be a striking presenting feature of thyrotoxicosis, but these cases provide reassurance to the clinician that when this does occur, other clinical features of hyperthyroidism are usually present.