Development of an abdominal aortic aneurysm (AAA) may be a product of generalised atherosclerosis. If that is indeed the case, we would expect similarities in various risk factors and other markers in common with occlusive peripheral arterial disease (peripheral arterial disease), and less congruity with healthy controls. To test this hypothesis, we recorded the major risk factors for atherosclerosis, two markers of endothelial dysfunction, and soluble adhesion molecules in 21 patients with an uncomplicated AAA free of symptomatic peripheral arterial disease, 42 patients with peripheral arterial disease, and 42 healthy controls who were matched, as a group, for age and sex. After adjusting for smoking, there were no significant differences in blood pressure, fibrinogen, soluble intercellular adhesion molecule-1, soluble vascular cell adhesion molecule-1 or lipoproteins between the groups. However, markers of endothelial integrity von Willebrand factor and soluble thrombomodulin were both higher (P< 0.05) only in peripheral arterial disease patients. Relative to the controls, platelet marker soluble P-selectin was increased in AAA (P< 0.01) and in the peripheral arterial disease patients (P< 0.05). Levels were higher in AAA patients than in peripheral arterial disease patients (P< 0.05). Our laboratory data suggest that the pathophysiology AAA and peripheral arterial disease are not identical.