Abnormal cerebrovascular regulation has been implicated in the pathogenesis of migraine. Our aim in this study was to evaluate cerebrovascular reactivity to different stimulations in migraine with and without aura. Using bilateral transcranial Doppler, the changes of flow velocity during hypercapnia and mental and motor activity were measured in the middle cerebral adages of 15 controls and 30 patients with migraine with aura (n=l5) or without aura (n=15) in an attack-free period. Vascular response to all tests was similar in controls and patients. In patients with unilateral headache, no side-to-side difference was found. These findings suggest that no alteration of cerebrovascular reactivity exists outside attacks in migraine with and without aura. Further studies with transcranial Doppler considering all intracranial vessels and the comparison with other techniques of flow investigation with better regional resolution are needed to confirm these data.