Some patients with aneurysmal subarachnoid hemorrhage (SAH) never reach the hospital alive ("sudden death") and, although their numbers are significant, they are not included in most studies of SAH. To clarify the clinical profile of sudden death from aneurysmal SAH, we reviewed the epidemiology and clinicopathologic features of patients with aneurysmal SAH who never reached medical attention. Using the medical record linkage system employed for epidemiologic studies for the population of Rochester, Minnesota, we identified all patients who were diagnosed with aneurysmal SAH between 1960 and 1989. There were 80 women and 33 men with a mean age of 55 years. Of these 113 patients, 13 (12%) died without reaching medical attention. The proportion of those with sudden death remained stable during the study period. In comparing patients with sudden death with those who reached medical attention, the only significant variable was the frequency of posterior circulation aneurysms that was found in 38%, compared with 14% in those who received medical attention (p = 0.042). At autopsy, intraventricular hemorrhage was present in 12 patients (92%) with sudden death, and intracerebral hemorrhage was present in two (15%). Twelve patients (92%) had acute pulmonary edema. In our community, the frequency of sudden death from aneurysmal SAH has not changed during the last three decades in spite of the advances in medical care. The typical clinical profile of sudden death in SAH includes intraventricular hemorrhage, pulmonary edema, and a ruptured posterior circulation aneurysm. Intracerebral hemorrhage is uncommonly associated with sudden death from aneurysmal SAH.