The authors describe the computed tomography (CT) and magnetic resonance imaging (MRI) findings in a patient with thrombosis of the inferior vena cava (IVC) and azygous continuation of the IVC caused by bronchogenic carcinoma. CT has been touted as the modality of choice for mediastinal evaluation. MRI is presently considered to be the initial modality of choice for mediastinal vessel evaluation. MRI is noninvasive, there is no radiation dose to the patient, multiplanar imaging can be done, and there is no need for iodinated contrast material. The satisfactory evaluation of an individual patient may require the use of MRI and CT in a complementary fashion.