Background Migraine patients can be sensitive to external or internal stimuli, such as light, noise, or hormonal changes.Using transcranial Doppler ultrasonography (TCD) with breath-holding method, we evaluated the changes of cerebrovascularreactivity (CVR) to hypercapnia in women with migraine without aura between fasting and postprandial period. Methods:Twelve women with migraine without aura and the same number of age and sex-matched healthy controls with no significanthistory of headache participated in this study. Using TCD examinations, we studied mean flow velocity in middle cerebralartery with better temporal window. Each subject was examined consecutively before and after a standard meal, togetherwith serum glucose level and blood pressure. CVR was evaluated with breath-holding index (BHI). Results: Postprandial-BHI(mean+SD) was significantly higher than fasting-BHI (mean+SD) in patients group but not in controls (in patient group;postprandial-BHI=1.38, fasting-BHI=1.08, in control group; postprandial-BHI=1.25, fasting-BHI=1.18, P=0.021 and 0.239,respectively). After meal, serum glucose level was significantly enhanced but blood pressure was not in both groups. Serumglucose level of patients showed a tendency of mild positive correlation with BHIs (