Goal: To determine whether aneurysms of the cavernous internal carotid artery (CCA) cause major neurologic morbidity or death. Methods: Retrospective analysis of all patients with a spontaneous CCA evaluated by a referral multidisciplinary neurovascular service from 1981 to 2000. All patients had complete clinical neuro-ophthalmologic and neurologic examinations and magnetic resonance imaging (MRI) or computed tomography (CT) with angiographic diagnostic confirmation. Follow-up evaluations were performed by our service in the majority of patients, and the remaining patients' subsequent examinations were obtained from the referring physicians. Results: One hundred seventy-four patients (mean age 60.7 years, median age 63 years, 161 women, 13 men) had 193 CCA. All 19 patients with bilateral CCAs were female. Twenty-eight patients had 1 or more subarachnoid aneurysms. The presentation included 156 aneurysms with pain or cranial neuropathy or both, 13 with a carotid cavernous fistula (CCF), and 24 asymptomatic CCAs. Two patients, both with a coagulopathy, had a cerebral infarct ipsilateral to the CCA, 1 at presentation and the other 2 years after partial third nerve palsy. One patient had a subarachnoid hemorrhage (SAH) 2.3 years after presentation, and no patient had arterial epistaxis or a CCA-related death. Excluding the 15 patients (16 aneurysms) who had no follow-up or died from SAH due to a subarachnoid aneurysm, 177 aneurysms were followed up for a mean duration of 3.10 years (SD = 3.6). One hundred six never-treated aneurysms were followed for 4.5 years (SD = 3.80, range 0.1-17), and 71 ultimately treated aneurysms were followed for 1.56 years (SD = 2.69, range 0.1-15). The overall rate for SAH was 0.19% and for a CCA-associated cerebral infarct was 0.37% per patient year. There were no correlations with cerebral infarct, SAH, or CCF and diabetes mellitus, hypertension, gender, age, cranial neuropathy, or size of the aneurysm, except for the largest diameter of the aneurysm and CCF (r = 0.17, P = .018). However, all of the patients with cerebral infarct or SAH and 12 of the 13 CCF had an aneurysm diameter ≥1 cm. Conclusions: CCA is a disorder with strong female gender bias that uncommonly causes major neurologic complications. These data suggest that CCA should not be included in analyses that determine the risk of severe neurologic morbidity, hemorrhage, or death due to intracranial aneurysms. Copyright © 2002 by National Stroke Association