Six patients for whom computed tomography revealed a curvilinear calcific mass anterior to their brainstem were evaluated and magnetic resonance imaging and magnetic resonance angiography were performed on each. Magnetic resonance studies confirmed the suspicion of basilar artery dolichoectasia, and demonstrated a partial thrombus in the basilar artery in 1 patient. The patients' clinical features were combined with those of basilar artery dolichoectasia patients reported in the literature (n = 122) who had case histories sufficiently detailed enough to determine each person's mode of clinical presentation. Basilar artery dolichoectasia patients were more often men (95/128, 74%) and had a mean age of 59 +/- 11 years. Of the 128 patients studied, there were cranial nerve compressive signs in 74 (58%), especially facial spasm (29/74, 39%) and trigeminal neuralgia (20/74, 27%); vertebral basilar insufficiency or vertebral basilar stroke or both in 61 (48%); hydrocephalus in 40 (31%); compressive brainstem symptoms and signs that progressed clinically in 31 (24%); and arterial hypertension in 31 (24%). Magnetic resonance imaging and magnetic resonance angiography safely diagnose this interesting arterial abnormality. The modes of clinical presentation of this disorder are reviewed.