The role of cerebrovascular risk factors such as mitral valve prolapse, platelet aggregation, platelet activation and cardiac arrythmias in migraine was investigated in a total of 44 migraineurs (32 migraineurs without aura and 12 with prolonged aura) and 32 controls. Comparing the total of migraineurs and the two subgroups with controls, mitral valve prolapse, a raised thromboxane B2 level, at least one platelet aggregation dysfunction or an abnormality in 24-h ECG was statistically seen no more often than in the control group. Neither did combinations of the variables occur more frequently. Altogether, this study showed no increased coincidence of migraine with prolonged aura and migraine without aura with the above parameters. The absence of cardiac and haematological abnormalities in migraine with prolonged aura focuses attention on the control of the cortical microcirculation.