Fourteen patients with a variety of aortic diseases were evaluated with magnetic resonance imaging (MRI). These included abdominal aortic aneurysms (eight cases), aortoiliac aneurysm (one), thoracoabdominal aneurysm (one), aortic dissections (four), and Takayasu arteritis (one). The size and extent of aneurysms, the presence of thrombus or atherosclerotic debris, the relation to renal and iliac arteries, and the effect of aneurysms on adjacent structures were readily demonstrated by MRI. The size of the residual lumen in a variety of vascular diseases and abnormal blood flow patterns could be assessed. In aortic dissection, MRI permitted identification of intimal flaps and determination of the origin of aortic branches from either of two lumina. Thickening of the wall and luminal narrowing of the aorta and arch vessels in Takayasu arteritis were clearly defined. These early results indicated that MRI achieved precise and complete assessment of a number of aortic abnormalities without the administration of any type of contrast material. Thus, early experience suggests that an important application of MRI will be as a totally noninvasive and reliable method for evaluating aortic disease.