Contrast media have been used for the study of disease of the thorax. Most experience has consisted of the use of MR contrast media for improving the delineation of acute myocardial infarction, for demarcating the area of acute myocardial ischemia, and for demonstrating the area of potentially jeopardized myocardium after acute coronary occlusion. Contrast agents demonstrate the ischemic or jeopardized area as a zone of decreased signal intensity to normal myocardium. On the other hand, the magnetic susceptibility agents demonstrate the ischemic or jeopardized area as a zone of increased signal intensity to normal myocardium. Little experience exists concerning the use of MR contrast media for enhancing mediastinal and lung masses. The few reports to date demonstrate that contrast media can improve the conspicuity of thoracic masses. A new nonionic contrast medium, gadodiamide injection, has been shown to considerably increase S/N and C/N of thoracic masses. Further studies are necessary to define the role of MR contrast media in the evaluation of myocardial ischemia and thoracic masses in clinical practice.