Whole-body computed tomography (CT) was performed in 600 patients with known or suspected malignancy. This new diagnostic modality utilizes a finely columnated X-ray source mounted opposite a computer-linked detector bank to generate anatomic cross-sectional images of the body part being scanned. CT proved valuable in defining many pathologic processes and was, at times, deemed the only test short of exploratory surgery that yielded diagnostic information. This latter benefit was most acutely emphasized in lesions affecting the retroperitoneum, adrenal glands, pelvis, liver and immediate subpleural pulmonary parenchyma.