OBJECTIVE - To analyse the benefits of screening older men for abdominal aortic aneurysms. METHODS - A hospital based screening trial concerning 13 500 65-73 year old men using B-mode ultrasonographic scanning. To improve the response rate the invited men could change their appointment, and nonresponders were reinvited. RESULTS - Results from the first year of the trial are presented. Among 4404 invited, 3344 (76%) were scanned. The primary response rate was 64.8%, but a further 11.2% were scanned after revised appointments or reinvitation. The whole infrarenal aorta could be visualised in 97-6%, and the distal part in 99.7% of the scans. The time taken for each scan was 9-7 minutes and the costs per scan were $9.50. One hundred and fifty three subjects (4.6%) had aortic diameters of 25-29 min, and 141 (4.2%) had an abdominal aortic aneurysm, 19 (0.6%) above 49 mm in diameter. CONCLUSION - In Denmark the short term costs and benefits of screening older men for abdominal aortic aneurysms seem realistic. Long term costs and benefits need to be investigated.