The incidence of abdominal aortic aneurysms (AAA) and ruptured AAA is increasing. One to three percent of deaths among 65-80 year-old males are caused by AAA. Sixty-six to ninety-five percent of ruptured AAA are lethal, while elective resection has a 3-6% operative mortality. Most AAA's are asymptomatic before rupture. Ultrasonographic scanning of the aorta takes below ten minutes with close to 100% sensitivity and specificity. The County of Viborg has started a randomized screening trial including 13,500 65-73 year-old males. Half of these are invited to the nearest hospital over a period of three years. In 1994-1995 4938 were invited and 3748 were scanned, resulting in an acceptance rate of 76%. The aorta was visible in 99.7%, and the total time consumption was 9.7 minutes per scan. The costs were 83.75 DKK per scan. One hundred and fifty-three (4.1%) had an AAA defined as an aortic diameter above 29 mm. Twenty were above 49 mm and were offered operation, i.e. 5.3 per thousand scans or 13% of the diagnosed AAA.