Aneurysm of the internal carotid artery is a rare disease and is known to be associated with congenital arterial anomalies such as neurofibromatosis type Ⅰ (NF-Ⅰ). NF-Ⅰ is an autosomal dominant neurocutaneous disorder characterized by a variety of manifestations that involve the central and peripheral nervous systems, skin, vascular system, and skeleton. In particular, the involvement of vascular abnormalities in NF-Ⅰ is well known. Any vessel may be affected by this condition, although the renal artery is most frequently involved. The vascular abnormality can be occlusive or an aneurysmal degenerative change. Therefore, symptomatic presentations might assume an indolent pathophysiologic course such as hypertension, or manifest as a catastrophic event such as arterial rupture that could result in sudden death. We report a rare autopsy case of an aneurysmal rupture of the internal carotid artery in a woman with suspected NF-Ⅰ, who collapsed in her home.