Background and Purpose— The goal of this study was to investigate predictive preictal risk factors for fatal subarachnoid hemorrhage (SAH) in a patient population with verified intracranial aneurysms without surgical selection of patients and with complete follow-up. Methods— A total of 142 patients with 181 unruptured aneurysms diagnosed between 1956 and 1978 were followed up for a total of 2577 person-years until death, SAH, or the years 1997 to 2000. The predictive value of several factors known before SAH was tested for case fatality. Results— During follow-up, 34 first episodes of hemorrhage from a previously verified unruptured aneurysm occurred. Of these bleeding episodes, 17 were fatal. Patients who died after the bleeding had higher blood pressure values (mean±SD, 148±11/92±8 mm Hg; mean pressure, 111±9 mm Hg) before hemorrhage than did those with nonfatal bleeding (mean±SD, 135±15/83±11 mm Hg; mean, 101±12 mm Hg) ( P <0.05). Patients with fatal SAH were also older (54±7 versus 47±13 years, P =0.068) and had aneurysms larger in diameter (13±8 versus 10±5 mm) than those who survived. They had a higher prevalence of definite hypertension (56% versus 12%, P <0.05), more frequently used antihypertensive medication (29% versus 6%) by the end of follow-up, and tended to have higher blood pressure at the beginning of follow-up (140±21/85±11 versus 134±17/80±9 mm Hg). After adjustment for age, aneurysm size, and sex, the only indisputable significant independent risk factor for fatal SAH compared with nonfatal SAH was systolic blood pressure before aneurysm rupture (odds ratio, 1.11 per 1 mm Hg; 95% CI, 1.01 to 1.23; P =0.032). The adjusted odds ratio of definite hypertension for fatal SAH was 12.67 (95% CI, 1.53 to 104.70; P =0.018). Conclusions— Increased systolic blood pressure values and long-term hypertension before aneurysm rupture seem to predict fatal SAH independently of aneurysm size or patient age or sex at the time of rupture.