CADASIL is a monogenic form of cerebral small vessel disease that leads to ischemic brain lesions at mid-adult age. We studied arterial perforator blood flow velocity and pulsatility in CADASIL patients and matched controls. We found significantly lower velocity and higher pulsatility in the basal ganglia and in normal appearing white matter (NAWM) of the centrum semi-ovale (CSO) in patients compared to controls. Within patients, no differences in velocity and pulsatility were found between CSO NAWM and white matter hyperintensities. This shows that small vessel disease in CADASIL patients is reflected in abnormal small vessel function also beyond lesioned areas.