To evaluate the potential for preferential arterial enhancement at magnetic resonance (MR) aortography with an intravenous infusion of paramagnetic contrast material. Gadolinium chelates were administered intravenously (0.2 mmol/kg) during three-dimensional MR imaging (1.5 T) in 125 patients (77 male and 48 female patients, aged 4-86 years [mean, 66 years]) with suspected aorta or aortic branch vessel disease. Infusion for the duration of the MR acquisition resulted in significant preferential arterial enhancement without the confounding effects of excessive venous or background-tissue enhancement (P < 10(-5)). Angiographic or surgical correlation in 48 patients revealed an 88% sensitivity and a 97% specificity for detection of stenoses or occlusions and a 100% sensitivity and a 100% specificity for detection of aortic or iliac artery aneurysms. Preferential arterial enhancement is possible at MR aortography with an intravenous infusion of paramagnetic contrast material.