Obstructive lung disease and lung cancer are tobacco-related diseases that can remain clinically silent until late in the disease process. We sought to define the risk for incident lung cancer among a national cohort of US adults with and without obstructive lung disease. We studied participants in the First National Health and Nutrition Examination Survey, who had up to 22 years of follow-up. We classified subjects as having moderate or severe obstructive lung disease at baseline if the ratio of forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC) was less than 70% and the FEV1 was less than 80% of the predicted value. We also determined incident cases of lung cancer during the follow-up period. A total of 113 lung cancers occurred in the 5402 adults in the cohort. In the proportional hazards model adjusted for covariates of age, sex, race, education, smoking status, and duration and intensity of smoking, the presence of moderate or severe obstructive lung disease was associated with a higher risk for incident lung cancer (hazard ratio, 2.8; 95% confidence interval, 1.8-4.4). The presence of moderate or severe obstructive lung disease is a significant predictor of incident lung cancer in long-term follow-up. This finding may be useful clinically and in studies evaluating the utility of new tools for the early detection of lung cancer.