Treatment of certain cerebral aneurysms, caroticocavernous fistulae, and tumors of the neck or cranial base may involve therapeutic arterial sacrifice, which requires preoperative knowledge of the feasibility of permanent occlusion of the internal carotid artery (ICA) or vertebral artery or arteries. Retrospective study of transcranial Doppler ultrasonography-monitored angiographic balloon test occlusion and therapeutic sacrifice of the ICA or vertebral artery. We performed transcranial Doppler-guided balloon test occlusion in 136 patients at a procedural risk equivalent to that of conventional neuroangiography, and with correct prediction of the hemodynamic result of therapeutic arterial sacrifice in all instances. Patients with an immediate drop in ipsilateral middle cerebral artery (MCA) velocity to 65% or more of baseline values upon ICA balloon occlusion tolerated ICA sacrifice well, whereas hemodynamic infarction is likely in those with a corresponding drop in MCA velocity to 54% or less. When ICA balloon occlusion caused a drop in MCA velocity to between 55 and 64% of baseline, the pulsatility of the MCA signal had to be analyzed. Patients who tolerated bilateral vertebral artery closure had reversal of flow and an increase in velocity in the P1 section of the posterior cerebral artery. In 212 patient-years of observation after therapeutic arterial sacrifice, no de novo aneurysms formed. Angiographic balloon test occlusion with transcranial Doppler monitoring can be performed ultra-swiftly at a risk equal to conventional neuroangiography and with correct prediction of the hemodynamic outcome of arterial sacrifice. Elective therapeutic arterial occlusion is a safe and efficient treatment of large cerebral aneurysms and caroticocavernous fistulae.