In general, computed tomography (CT) is superior to magnetic resonance imaging (MRI) as an all-around tool for imaging the wide range of thoracic abnormalities that can be present in patients with lung cancer. However, CT and MRI should not necessarily be viewed as competitive imaging modalities in this clinical setting. If MRI is used selectively as a secondary imaging study to answer specific questions raised or unanswered by CT, its value can be optimized. It can be of particular value in demonstrating chest-wall invasion in the lung apex as well as elsewhere, in defining mediastinal masses, which are hard to distinguish from vessels on CT, in detecting hilar masses, in distinguishing causes of adrenal mass, and in distinguishing recurrent tumor from fibrosis in patients who have had prior radiation.