Botulinum toxin type A (BT-A) has been described as an important strategy to various types of pain such as cervical dystonia, myofascial pain syndrome and headache. Although BT-A efficacy has not been proven in tension type headache, its use in migraine continues controversial. In this open trial, we evaluated the efficacy of BT-A in refractory migraine. BT-A was injected in patients diagnosed with migraine who had previously used three classes of prophylactic drugs by at least one year with no response. The most important improvement was observed within 30 days, but pain intensity and frequency of headache had been decreased until the end of three months of follow up. Side effects of BT-A were mild and self limited. We conclude that BT-A seems to be a safe and effective treatment to refractory migraine patients.