The authors conducted a population-based case-control study of lung cancer in nonsmoking women in five metropolitan areas of the United States between December 1, 1985, and November 30, 1990. In-person interviews were conducted with 412 lung cancer cases and 1,253 population controls, yielding information on history of nonmalignant lung diseases that were diagnosed by a physician. When lung cancer cases were compared with controls, history of any previous lung disease was associated with a significant increased risk of lung cancer (adjusted odds ratio (AOR) = 1.56, 95% confidence interval (CI) 1.2-2.0). Several lung diseases, including asthma, chronic bronchitis, pneumonia, and tuberculosis, were reported more often by lung cancer cases than by controls, and the difference was statistically significant for asthma (AOR = 1.67, 95% CI 1.1-2.5) and chronic bronchitis (AOR = 1.60, 95% CI 1.1-2.4). Since significant increased risks were observed for asthma and tuberculosis diagnosed before age 21 years, it is unlikely that reported prior lung diseases were prediagnostic manifestations of lung cancers. The increased risks associated with previous lung disease were observed for adenocarcinomas and other carcinomas of the lung; the point estimates were generally higher for the latter category. The risks associated with previous lung diseases remained unchanged after adjustment for potential confounders, including environmental tobacco smoke exposure during childhood and adult life and dietary factors.