Among the exposures associated with risk for lung cancer, a history of tuberculosis is one potentially important factor, given the high prevalence of tuberculosis worldwide. A prospective cohort study was conducted to evaluate the associations of preexisting pulmonary tuberculosis with lung cancer incidence and mortality. The cohort consisted of 1,607,710 Korean adults covered by the National Health Insurance System who had a biennial national medical examination during 1997-2000. During up to 16 years of follow-up, there were 12,819 incident cases of lung cancer and 9,562 lung cancer deaths. Using Cox proportional hazards models and controlling for age, cigarette smoking and other covariates, the presence of underlying tuberculosis was significantly associated with increased risk for lung cancer incidence (HR 1.37 in men with 95% CI 1.29-1.45; HR 1.49 in women with 95% CI 1.28-1.74) and mortality (HR 1.43 in men with 95% CI 1.34-1.52; HR 1.53 in women with 95% CI 1.28-1.83). We also observed a dose-response relationship between number of cigarettes smoked daily and lung cancer risk. There was no evidence for synergism between a history of tuberculosis and smoking. The elevation in risk is relatively modest, particularly in comparison to that from smoking, and a prior history of TB is not likely to be useful risk indicator for clinical purposes. In populations with high prevalence of tuberculosis, it can be considered for incorporation into models for lung cancer risk prediction. This article is protected by copyright. All rights reserved.