Small pulmonary nodules of soft tissue density are often found during computed tomography for the staging of lung cancer, but CT cannot reliably distinguish benign from malignant uncalcified pulmonary nodules. The purpose of this study was to assess the significance of pulmonary nodules discovered on staging CT. 551 patients with lung cancer who had a staging CT and who were considered operable were studied. Eighty-eight patients (16%) were found to have small non-calcified pulmonary nodules. Adequate follow-up was possible in 25 patients who had a total of 36 nodules. Twenty-five nodules (70%) were subsequently confirmed to be benign, four (11%) were malignant and the nature of seven (19%) could not be determined. The high prevalence of benign nodules in this population should be taken into account when staging lung cancer.