To evaluate the sensitivity of computed tomography (CT) in detecting multicentric primary bronchogenic adenocarcinoma manifesting as a pulmonary nodule, the authors reviewed CT scans and pathologic specimens of 158 consecutive patients who underwent resection of a pulmonary nodule. Two independent observers assessed the scans without knowledge of the pathologic findings. Lung specimens were fixed in inflation and sectioned transversely, analogous to the plane of the CT scans. In 88 patients the nodule represented adenocarcinoma. Multicentric adenocarcinoma was present in 19 of these patients (22%). The sensitivity of CT in correctly detecting the presence and location of two or more lesions was 0.63 and 0.68 for two observers, with a specificity of 0.86 for both. The CT appearance of multicentric disease varied from well-defined nodules to ill-defined hazy opacities simulating pneumonitis. The data indicate that (a) multicentric adenocarcinomas are more common than generally reported in the literature and (b) meticulous evaluation of CT images enables detection of multicentricity in a high percentage of cases.