A thirty-four-year-old male, with a ten-year history of typical common migraine, had, on three occasions, typical migraine headaches which were associated with vomiting. During each of these episodes, atrial fibrillation was documented. Cardiac rhythm was normal between episodes. In this case, we feel that the atrial fibrillation was secondary to an increase in vagal tone resulting from vomiting. We doubt that the migraine itself was responsible for the atrial fibrillation. We propose that the association of migraine and atrial fibrillation be treated by control of vomiting. Where vomiting is hard to control, then atropine given on a prophylactic basis may also be helpful, as atropine is shown to be effective in the prophylaxis of atrial fibrillation when it is secondary to an increase in vagal tone.