Lung cancer risk associated with family and personal history of respiratory diseases was assessed in a population-based, case-control study that included incident cases in New Mexico, 1980 to 1982. The study questionnaire ascertained previous diagnoses of major chronic respiratory diseases in the index subjects, their parents, and their grandparents and of lung and other respiratory cancers in the parents and grandparents. Physician diagnoses of chronic bronchitis, emphysema, asthma, and other chest illnesses were reported significantly more often for cases than for control subjects. For 6.9% of the cases, at least 1 parent had a diagnosis of lung cancer, whereas only 2.2% of the control subjects' parents were similarly affected (p less than 0.001). In multiple logistic regression models that excluded never smokers and included variables to control for the effects of cigarette smoking, we found significantly increased risks for a personal history of chronic bronchitis or emphysema (odds ratio = 2.0; 95% confidence interval, 1.4 to 2.8) and a parental history of lung cancer (odds ratio = 5.3; 95% confidence interval, 2.2 to 12.8). The present study complements the results of previous investigations, which demonstrated that lung cancer risk in smokers is modified by characteristics of the smoker and by family history.