Among 18,403 male civil servants examined at age 40-64 years there were 99 deaths attributed to aortic aneurysm during 18 years of follow-up. Each case was matched by age to ten controls who survived longer than the case. The risk of all types of fatal aneurysm was substantially increased for current smokers of manufactured cigarettes (rate ratio compared with lifelong non-smokers = 6.5; 95 per cent confidence interval 2.3-18.7), pipe or cigars (6.7; 1.7-26.5) and hand-rolled cigarettes (25.0; 7.5-83.3). Diastolic blood pressure was strongly associated with dissecting aneurysm (rate ratio per 10 mmHg increase = 2.4; 95 per cent confidence interval 1.7-3.2) and abdominal aneurysm (1.5; 1.2-1.9) but not other aneurysms (1.0; 0.7-1.5). The independent effects of height, adiposity, plasma cholesterol, glucose intolerance, reported angina and intermittent claudication were not significant. Hypertension and smoking, particularly of hand-rolled cigarettes, are confirmed as major and potentially remediable risk factors for fatal aortic aneurysm.