Magnetic resonance imaging (MRI) provides noninvasive functional information as well as a three-dimensional anatomic display of the cardiovascular system. MRI of protons, phosphorus, or sodium nuclei is currently being investigated to characterize cardiovascular pathology, and the potential benefits of paramagnetic contrast agents are becoming apparent. Finally, techniques to quantitate blood flow, vascular pressures, chamber volumes, ventricular ejection fractions, and cardiac output are being developed.