Dignosis of migraine is only based on the medical history, and objective methods to aid the clinical diagnosisare absent. Although transcranial Doppler ultrasonography (TCD) abnormalities in headache-free migraineurs have been reported previously, diagnostic criteria for migraine is still lacking and this may limit the practication of TCD for migraine. we prospectively studied several abnormal TCD indices in interictal migraineurs and their sensitivity and specificity to define the optimal diagnostic criteria. Young (20 yrs