&NA;Microvascular Doppler recordings were taken from the nidus and draining system of a dural spinal cord arteriovenous malformation during operative treatment. Doppler signals readily showed the direction of blood flow in the draining vein and the hemodynamic effects of surgical maneuvers. Recording during alterations of mean arterial blood pressure and partial carbon dioxide pressure (pCO2) demonstrated lack of autoregulation and impaired CO2reactivity in the AVM nidus. Microvascular Doppler techniques provide useful intraoperative assessment of the hemodynamics of arteriovenous malformations of the spinal cord. (Neurosurgery25:270‐275. 1989)