Both CBF and CBV were evaluated by gamma-camera SPECT in 14 patients with classic migraine, all studied while symptom-free. Nuclear data were correlated with CT and MRI. A decreased regional CBF was observed in 13 of the 14 patients. The decreased perfusion was localized in the frontal lobe in 6 patients, the temporal lobe in one, the parietal lobe in 11 and the occipital lobe in 5 patients. The parieto-occipital cortex was involved more often than the frontal cortex; the association of hypoperfusion with parieto-occipital cortex was quite high. The right parieto-occipital regions were affected more often than the left ones. Regional CBV was increased in 8 patients. There was good topographical concordance between decreased CBF and increased CBV, but the increase of CBV was in general more evident at the periphery of the hypoperfusion. It is of interest that the only patient with a normal CBF study had a pathological CBV study. Apparently, CBF derangements are very common in symptom-free patients with classic migraine, a CBF decrease being often accompanied by a CBV increase. In these patients both CT and MRI have a lower diagnostic yield than SPECT.