The authors conducted a clinical observation of 55 cases of solitary pulmonary nodules at Yeungnam University Hospital from June 1986 to October 1990, and the following results were obtained : 1. The age distribution was ranged from 18 to 77 years, and the male-to-female ratio was 1.8:1. 2. Among 55 cases of nodules, 28 cases were benign and 27 cases were malignant nodules, and of malignant nodules, the primary lung cancer was 23 cases and of benign nodules, 18 cases were tuberculoma. 3. 23 cases (41.8%) was asymptomatic and the other 32 cases were symptomatic; chest pain 12 cases, hemoptysis; 8 cases, cough; 8 cases and dyspnea; 4 cases. 4. The non-smoker-to-smoker ratio was 1:1.04, but among 23 smoker over 20 pack years, 14 cases were malignant nodules. 5. According to nodular size, there is no striking differences between benign and malignant nodules except 3-4cm sized nodules. 6. The lobar distribution of nodules, 35 cases were in the right lung (upper lobe; 14 cases, middle lobe; 11 cases, and lower lobe; 10 cases) and 20 cases were in the left lung(upper lobe; 9 cases, lower lobe; 11 cases), and the malignant nodules were most commonly observed in the right upper lung.