To assess the efficacy of performing both computed tomography (CT) of the thorax and upper abdomen and whole-body gallium scintigraphy for staging lung cancer, the results of each test were compared with those obtained by chest radiography and clinical examination in 100 patients. Clinical efficacy was defined in terms of accuracy in staging the tumor based either on surgery, biopsy, or clinical and radiologic follow-up. The CT provided significantly superior accuracy in 27 patients and minor additional staging information in 17 patients compared with the gallium scan. Whole-body gallium scintigraphy provided important additional information in nine patients and minor additional information in a further eight. The diagnostic yield of CT and gallium scanning was considered equivalent in 39 cases. Of the nine cases in which gallium was significantly superior to CT, clinical findings which suggested the presence of metastases had been noted before the scan in four cases. The authors' results confirm the utility of CT for staging lung cancer and indicate that the additional yield from gallium scintigraphy is relatively low provided a thorough history and physical examination have been performed.