Abdominal aortic aneurysm is common. The aim of this study was to assess the effect of smoking on prevalence and management. Patients attending the vascular unit and appropriate controls were prospectively recruited. A smoking history revealed tobacco exposure in pack years. Serum cotinine was assessed biochemically. Independent risk factors were statistically determined. In all, 202 (186 men) patients were recruited, with 202 (197 men) controls. A total of 69 patients tested positive for cotinine, whereas 39 controls were positive (P = .001). Smoking and ischemic heart disease were significant predictors for aneurysm prevalence. Cardiac disease emerged as a more important predictor than smoking in symptomatic patients. In noncardiac patients, smoking and hypercholesterolemia were significant risk factors. Smoking is a significant predictor for aneurysm development. In high-risk patients, the cardiac disease process is the most important factor, with control of this imperative. However, in noncardiac patients, smoking cessation and lipid-lowering therapy are crucial.