PURPOSE: Lung cancer is now one of the most frequently diagnosed cancers in the world and its incidence has been increasing also in Korea. In several recent studies, the indidence of adenocarcinoma and female/male ratio have been reported to be increasing. The aim of this study is to investigate the changing trends in sex and age distribution, the histologic type and location (peripheral or central) of tumors in lung cancer. MATERIALS AND METHODS: We performed the retrospective review of histopathology and clinical information of 1409 patients diagnosed as baving primary lung cancer, except non-epithelial tumors and undetermined histologic types, at Kyungpook National University Hospital from January 1988 to December 1996. RESULTS: Male to female ratio was 4.6; 1. The peak incidence of age group was 7th decade (40.3%) with mean age of 61.5. Percentage of smokers in patients with lung cancer was 84.3%. Total number of patients with lung cancer has increased recently. However, the annual female/male ratio was nearly constant during the study period. Peripheral tumors, which were found in 20.6% of patients with lung cancer in 1988, increased to 33.5% in 1996 and this trend was more prominent in squamous cell carcinoma than in adenocarcinoma. Squamous cell carcinoma was the most common histologic type (62.0%), followed by adenocarcinoma (19.2%), small cell carcinoma (14.2%), large cell carcinoma (4.6%) in order. There was a predominance of squamous cell carcinoma (67.9%) in males and of adenocarcinoma (46.6%) in females. There has been a significant shift in the histology pattern with an increase in the percentage of adenocarcinoma. The incidence of adenocarcinoma was more than doubled from 7.5% in 1988 to 25.8% in 1996. CONCLUSION: These findings suggest that the epidemiology of lung cancer is changing.