Incomplete combustion of coal in homes has been linked with lung cancer in China. We report on a lung cancer case-control study in a rural area of China, where many residents live in underground dwellings and burn coal and unprocessed biomass (crop residues, wood, sticks, and twigs) for heating and cooking. We interviewed 846 patients with lung cancer (626 men, 220 women; aged 30 to 75 years) diagnosed between 1994 and 1998, and 1740 population-based controls. The odds ratio for lung cancer associated with coal use compared with that for biomass in the house of longest residence was 1.29 (95% confidence interval, 1.03 to 1.61), adjusted for smoking and socioeconomic status. The risk for lung cancer increased relative to the percentage of time that coal was used over the past 30 years (P= 0.02). Our findings suggest that coal may contribute to the risk of lung cancer in this rural area of China.