The case is reported of a patient with human immunodeficiency virus (HIV) infection presenting with isolated headache as the presumed manifestation of a cavernous carotid aneurysm. The relationship between HIV and aneurysms is discussed. Clinicians should be aware of the possibility of carotid aneurysms in HIV-positive patients, even in areas where HIV is not endemic and when no neurological deficit is present. Magnetic resonance imaging is recommended as the initial diagnostic study.