We studied cerebral blood flow (CBF) with the 133xenon inhalation technique in 92 migraine patients (49 classic/complicated, 43 common), aged 19 to 85 years, in the headache-free period. We compared results to 49 control subjects, aged 22 to 80 years. CBF declined with age in both groups, but at a slower rate in migraine patients, a difference most pronounced in classic migraine. CBF was lower in migraine patients than in controls under 48 years of age. In addition, regional asymmetry of blood flow was found more frequently in young migraine patients than in controls. These results suggest that differences exist in cerebrovascular resistance tone in migraine patients, which may contribute to the threshold for a migraine attack and result in differing age-related changes in blood flow.