Fifty patients with clinically suspected lesions of the chest apex underwent computed tomography (CT) and plain film (PF) examinations in an attempt to define the underlying etiology as benign or malignant. CT was slightly more sensitive in diagnosing malignancy (90%) compared with PF (77%), with a higher predictive value of a negative test (85% vs. 70%), although the differences were not statistically significant. The specificity and predictive value of a positive test were similar for CT and PF. CT's advantage was better elucidation of the soft tissues of the chest apex. CT provided additional information beyond PF in 17/20 patients with benign conditions and in 29/30 patients with cancer. In 21 of these 29 cancer patients, CT findings significantly altered subsequent management.