In this report we describe a comatose patient with proximal aortic dissection who presented with the signs of subarachnoidal hemorrhage. Shortly before losing consciousness, the patient complained of an excruciating headache. Upon initial examination, neck stiffness and opisthotonos were present. The cardiovascular examination, chest radiograph, and cerebral computed tomography were normal. Eight hours later, the aortic dissection was verified by a thoracic computed tomography. This case shows that aortic dissection, which causes severe pain and possibly transient malperfusion of the carotid arteries, may present with the misleading signs of subarachnoidal hemorrhage but without classical symptoms of aortic syndromes.