BACKGROUND: Lung cancer continues to increase and one half of all cases of lung cancer occur in patients age 65 years and older. However, it seems that lung cancer is less treatable in elderly patients because of co-morbid illness or poor tolerance of surgery and chemotherapy. The intention of this study is to seek an adequate treatment approach for lung cancer in the elderly through an understanding of its characteristics. METHOD: The clinical data of 207 patients who were diagnosed with histologically proven lung cancer at the department of internal medicine in Seoul Municipal Boramae Hospital between September 1994 and August 1998 were retrospectively analyzed according to their age groups; group I >or=65 years (n=122) and group II <65 years(n=85). RESULTS: The peak incidence of age was 7th decade(36.2%) and male age 65 years and older were 42% of all patients. Although dyspnea was more common in group I (26%) than in group II (11%)(p=.01), there were no significant difference in other symptoms, stage, and histologic type between two groups. Group I significantly had more patients with poor performance(ECOG 3 and 4) than group II (35.2% vs. 12.9%, p=.000). The percentage of patients with non-small cell carcinoma received supportive care only was significantly higher in group I than in group II (74% vs. 35%, p=.000). However, survival of patients who had curative intent treatment was similar between two groups(median survival 11.3 mos vs. 23 mos, p>.05). The histologic subtype, stage and performance status were significant prognostic factors affecting survival, but age itself was not. CONCLUSION: Lung cancer is Prevalent in the elderly and aggressive diagnosis and treatment should be considered in elderly patients with good performance status.