The objective of this study is to explore the etiology and early risk evaluation of lung cancer in Xuanwei County, Yunnan Province of China. Polycyclic aromatic hydrocarbon (PAH)-DNA adduct in brushing cells from fibrobronchoscopy was determined in 30 cases with lung cancer in Xuanwei County and 10 controls in Kunming, Yunnan Province by 32P-postlabelling assay. Results showed that PAH-DNA levels in lung cancer patients of Xuanwei County were much more higher than those in controls. It suggested that air pollution caused by indoor coal-burning associated directly with the occurrence of lung cancer, and detection of DNA adduct could be used as an indicator for its risk assessment in population.