Computed tomography (CT) can provide a noninvasive alternative to pulmonary arteriography for pulmonary embolism in selected circumstances. Three cases that demonstrate the technique and initial clinical experience are reported. Illustrated are: (1) CT detection of massive central pulmonary thromboembolism in a critically ill girl in whom the risk of complications from pulmonary arteriography was considered especially high; (2) the use of CT for serial examinations for follow-up of central thromboembolism, avoiding repeat angiography; and (3) preoperative CT delineation of organized thrombus in the proximal right pulmonary artery, an area not adequately evaluated on selective pulmonary artery injections. CT effectively displayed emboli and thrombi in central pulmonary arteries in each patient. Its application to embolus detection in peripheral arteries was not investigated.