Computerized tomography (CT) was utilized as a preoperative screening procedure in a series of 50 patients with lung carcinoma who were neurologically asymptomatic and whose radionuclide brain scans and skull roentgenograms were normal. Three patients (6%) were discovered to have metastasis (cerebellum, occipital, corpus callosum). The metastatic lesions were only directly visualized after administration of contrast substance. The CT findings greatly influenced the therapeutic planning in these patients, and surgery was avoided in two. When feasible, patients with lung carcinoma should have CT examinations (with contrast administration) prior to thoracic surgery even if they do not have neurologic symtoms.