Transcranial Doppler, electroencephalography, and single photon emission computed tomography were performed in a case of basilar migraine during the different phases of the attack. In the aura phase, the patient had bilateral blindness and ataxia. Doppler ultrasound studies showed a reduction in the mean flow velocity of the posterior cerebral arteries, electroencephalography showed slow activity confined to the posterior regions, and single photon emission computed tomography, an area of hypoperfusion in the right parietal and occipital regions. During the headache phase, when the neurological examination was normal, transcranial Doppler showed an increase in the mean flow velocity of both posterior cerebral arteries and the electroencephalogram revealed an increase: in the slow activity over the occipital regions. When the pain subsided, the electroencephalogram showed a progressive reduction of the slow abnormalities and transcranial Doppler was reported as normal. After a week, single photon emission computed tomography and cranial magnetic resonance imaging were normal. After a month, a follow-up electroencephalogram was also normal. All these findings indicated a transient focal reduction of cerebral blood flow during the aura phase.