Dual-energy computed tomography (CT) was used to study apparently noncalcified pulmonary nodules in 19 patients. We obtained both high-and low-voltage images during one CT scan study using a special CT apparatus, and four of 11 benign lesions were diagnosed as benign by measurement of the CT number. Moreover, this particular CT apparatus was useful in judging the presence or absence of calcification in pulmonary nodules.