An abdominal aortic aneurysm is defined as the increase of infrarenal aortic diameter of 3.0 cm and more. Infrarenal aortic aneurysm is frequent in the elderly and causes 1-3% of all deaths among men aged between 65 and 85 years. These aneurysms are typically asymptomatic until the life threatening event of rupture. Therefore screening of risk populations like elderly persons and persons with cardiovascular risk factors for aortic aneurysm seems to be most important. An aortic aneurysm is usually detected by sonography. An infrarenal aortic aneurysm with a diameter of 5.0-5.5 cm should be treated either with open surgical or endovascular therapy. If surgical or endovascular therapy is indicated, additional computer tomography (CT) or magnet resonance imaging (MRI) are necessary. The mode of treatment mainly depends on patient co-morbidity and on morphology of the aneurysm according to the CT/MRI-findings and should be determined individually.