Computed tomography assessment of 634 surgically proven solitary pulmonary nodules included 12 pulmonary carcinoid tumors. Five were central (involving or directly abutting the bronchial tree), and seven were peripheral (surrounded by parenchyma). Three central and one peripheral lesion had CT numbers indicative of focal calcifications, frequently in the periphery of the nodule. Nodule size ranged from 1.2 to 3 cm. Nine nodules were smooth and round, two were irregular and lobulated, and in one the entire peripheral contour was difficult to assess because of postobstructive atelectasis secondary to tumor occlusion of the bronchus. The calculated average CT number ranged from 80.5 to 179 HU.