Ultrasound is presently the diagnostic procedure of choice in pulsatile abdominal masses. The ease and accuracy of this method have many advantages over aortography, and ultrasonography can accurately define the size of an abdominal aortic aneruysm. In addition, a normal aorta with an overlying mass, or a tortuous aorta which feels unusually prominent, can be detected, and aortography may not be necessary. Although ultrasound can detect involvement of iliac arteries, it does not allow assessment of the position of the aneurysm relative to the renal arteries, or detect involvement of other branch vessels of the aorta. Ultrasound is more accurate that clinical examination, plain roentgenography, aortography, or isotope aortography in the diagnosis of abdominal aortic aneurysms.