Based on clinical and histopathological Studios of 287 cases of primary carcinoma of the lung for 21 year-period from 1957 to 1977, following results are obtained. 1). The lung cancer has rapidly increased since early 1970th. 2) Among 287 cases, 133 cases (46. 4%) were epidermoid carcinoma, 74 cases (25.8%) were oat cell carcinoma, 34 cases (11.9%) were adenocarcinoma, 18 cases (6.3%) were large cell undifferentiated carcinoma, 6 cases (2.1%) were bronchiolo-alveolar cell carcinoma, and 2 cases(0.7% ) were bronchial adenoma. 3) The sex distribution showed male preponderance (3.9:1). 4) Among 136 cases whose smoking histories were available, 124 cases (91%) had smoked for over 10 years and among them 78 cases (57.4%) were epidermoid carcinoma. 5) The chief complaints were dyspnea, chest pain, coughing and weight loss, and paraneoplastic symptoms were observed in 2 cases. 6) The right lung showed slight preponderance (2:1). 7) Epidermoid carcinoma and oat cell carcinoma were found mostly at the hilum and central portion of both lungs. 8) Almost half (47%) of the cases had initially been treated as other benign diseases, such as pulmonary tuberculosis, common cold, broncitis and pneumonia before confirmative diagnosis of lung cancer. 9) The complications were pleural effusion, atelectasis and vocal cord paralysis in order of frequency. 10) Almost half (50.5%) of the lung cancer had metastasized to neck lymphnodes.