Thirteen patients with aortic aneurysm (abdominal 7, thoracic 4, thoraco-abdominal 2) were evaluated by magnetic resonance tomography using a super-conducting magnet of a field strength of 0.35 tesla in transversal, coronal and sagittal planes. ECG gating was used in patients with thoracic aneurysm. The results of magnetic resonance imaging (MRI) were compared to angiography, computed tomography (CT) and intraoperative findings. MRI demonstrated in all 13 patients the extent and the localisation of the aneurysm. The presence of mural thrombus was better determined by MRI (10/10) than by angiography (6/10). The relationship of the brachiocephalic arteries in thoracic aneurysm was better evaluated by MRI compared to angiography and CT. All 3 aortic dissections could be demonstrated by MRI. These first results may suggest an important role of MRI in the diagnosis of aortic aneurysms.