Objective and Design to assess if deletion of the angiotensin-converting enzyme (ACE) gene is a risk factor for abdominal aortic aneurysms (AAAs) in normotensive patients. Materials and Methods ACE gene polymorphism was examined by polymerase chain reaction in 124 subjects with AAA and in 112 control subjects. AAA normotensive patients (group A,n=56) were compared to normotensive control subjects (group B, n =112) and to AAA hypertensive patients (group C, n =68). All subjects enrolled in this study were Caucasian and from central and southern Italy.Results the distribution of ACE genotypes was: normotensive patients with AAAs (group A): 3 II, 14 ID, 39 DD; normotensive control subjects (group B): 36 II, 48 ID, 28 DD; hypertensive patients with AAAs (group C): 14 II, 32 ID, 22 DD. The DD genotype was more common in group A than in control groups (A vs B p<0.001; A vs C p <0.001). The ID genotype was more common in group A as well (A vs B p <0.05; A vs C p <0.005). Conclusions our data suggest a role for ACE I/D gene polymorphism in the pathogenesis of AAA in normotensive patients.