The study was carried out on 468 cases among total 4,347 cancer cases which was confirmly diagnosed as malignant neoplasms at Yonsei Center Hospital, appended to Yonsei University, during 10 years from January 1, 1971 to December 31, 1980. The results of this study are as follows: 1. Total malignant neoplasm cases treated with radiation were 4,347, 1,685 of whom were males, and 2,662 females(male to female ratio was 1:1.58). 2. Lung cancer were 10.8% of total malignant neoplasm cases(468 cases), 391 cases for the male and 77 cases for the female. So, average the male to female ratio was 8:1 and cases of the male were much more. 3. The age distribution of lung cancer cases was from 27 to 82 years old. The highest age distribution was $50{sim}59$ for males(37.9%) and $60{sim}69$ for females(41.6%) ; 77.1% of total lung cancer cases were over 50 years old. 4. In regard to stages, the distribution of the third stage was highest(49.3%). That of the first stage was much higher during the last period(11.8%) than the first period(2.7%), and that of the fourth stage was much lower during the last period (7.8%) than the first period(21.1%). 5. In regard to pathological type, the distribution was 51.3% for squamous cell carcinoma, 29.3% for undifferentiated cell cercinoma, 12.2% for adenocarcinoma, and 7.2% for bronchoalveolar cell carcinoma in order of frequency. In regard to adenocarcinoma, the male to female ratio was 1:3.7 and cases of the female were much more. 6. In regard to tumor location, the distribution of tumor location in the right-left lobe was 59.1% in the right lobe, 33.6% in the left lobe, and 7.3% in the both lobes in order of frequency. And that of tumor location in the upper and lower lobes was all higher in the upper lobe ; especially, that of the right upper lobe was highest(31.2% of total cases). 7. For the main symptom, coughing was highest(64%), 50% for hemoptysis, and 41% for dyspnea.