One hundred and twenty patients with bronchogenic carcinoma were prospectively studied by both computed tomography (CT) and magnetic resonance imaging (MRI) during the 2 weeks preceding thoracotomy or mediastinoscopy. MRI scans included contiguous axial and coronal slices. Results of CT and MRI studies were compared with the surgical and pathological findings on the basis of the TNM classification. Although no significant difference was found between the two imaging methods for the evaluation of tumour extent, MRI appears to be a valuable imaging technique for left upper lobe and apical neoplasms. Comparison between the two techniques for mediastinal node evaluation showed that sensitivity of MRI is superior to CT in the left paratracheal, aortopulmonary and subcarinal node areas.