It is well established that multiple influences regulate cerebral blood flow: the overwhelming evidence continues to suggest that migraine is a disorder, albeit temporary, of cerebral hemodynamics. Thus, the classical theory of migraine is no longer tenable as viewed strictly and rigidly. Perhaps it would be easier to say that the migraine's aura is characterized by reduction in blood flow, often hemispheric, and that sometime during the headache phase cerebral hyperperfusion occurs. The process is under the control of multiple factors: neurogenic, chemical, metabolic, and myogenic. The blood flow changes do not necessarily correlate with the patient's symptoms. Thus, even now, migraine and other vascular headaches remain as descriptive diagnoses. The final pathology of migraine remains to be determined.