The aim of this paper is to estimate the nationwide incidence rate of lung cancer in Korea. The potential incident cases were identified by hospital visiting and mailing, based on the ICD-9 diagnostic codes on the claims as one of the following: ICD-9 162-165 (malignant neoplasms of the respiratory system), 212 (benign neoplasm), 231 (carcinoma in situ), 511 (pleurisy), or 195-199 (malignant neoplasms with uncoded sites) in beneficiaries data of the Korea Medical Insurance Corporation from January, 1988 to December, 1989. Thereafter, the identified cases were confirmed by an oncologist (Dr. DS Heo). When adjusted with age distribution of the Korean population based on the 1985 Population Census, the incidence rate was 22.3 per 100,000 in males (95% CI: 21.70-23.01) and 8.37 (95% CI: 7.97-8.78) in females in 1989. And the age-adjusted rate for the world population was 39.63 in males and 9.95 in females.