Abdominal aortic aneurysms occur in 5 to 7 percent of people over age 60 in the United States. An aneurysm is defined as a permanent localized dilatation of an artery, with an increase in diameter of greater than 1.5 times its normal diameter. Abdominal aortic aneurysms may be manifested by catastrophic rupture, signs of pressure on other viscera or an embolism originating in the aneurysmal wall, but most cases are asymptomatic. The diagnosis is often made by physical examination of the abdomen, which reveals a pulsatile mass left of the midline, between the xyphoid process and the umbilicus. The diagnosis may be confirmed by B-mode ultrasound. Ultrasound screening should be considered for individuals at risk for abdominal aortic aneurysms. This group includes individuals over age 60 who smoke, have hypertension or have vascular disease. Elective surgical intervention is indicated for most patients with abdominal aortic aneurysms greater than 5 cm in diameter to prevent rupture and death. Smaller abdominal aortic aneurysms should be monitored by regular ultrasound measurements. Screening and identification of abdominal aortic aneurysms by primary care physicians can have a significant impact on patient survival.