Abdominal aortic aneurysm (AAA) is an increasingly common vascular disease affecting 2-9% of elderly people aged more than 65 years. Smoking has been considered an important risk factor associated with AAA development but the pathophysiological mechanisms which underly its adverse effects are uncertain. This project confirm previously reported AAA pathological characteristics namely a decrease in number of elastic lamellae, increased macrophage infiltration, decrease in VSMC density and increase of activity of proteases (MMP-2, MMP-9, MMP-12 and elastase). Cigarette smoking however, was associated with an increasing degree of elastin breakdown, macrophage infiltration and extent of MMP-12 activity in the aortic wall as well as increased plasma MMP-2 and elastase levels. The results support a direct relationship between the level of smoking and the extent of aneurysm aortic wall damage.