OBJECTIVES: The objectives of this study were to estimate the proportion of occupational lung cancer in the Busan area. METHODS: Occupational physicians of four university hospitals operating an occupational disease surveillance system in the Busan area actively interviewed all of the newly diagnosed, lung cancer cases about their characteristics and occupational histories through a survey questionnaire and chart review. To evaluate and agree on the work-relativity, the cases were presented in periodic meetings. RESULTS: A total of 301 lung cancer cases were interviewed, of which 50 (16.6%, all male, 27 probable and 23 possible) were related to occupational exposure. The exposure materials were asbestos, Cr, PAH etc. Pathologic findings included squamous cell carcinoma, adenocarcinoma and small cell carcinoma. CONCLUSIONS:The proportion of occupational lung cancer cases above the probable level was 9% and above the possible level was 17%. To develop the public health policy and to prevent further cancer death, the meaningful data from occupational cancer surveillance systems should be collected continuously for ongoing monitoring.