The relation of ventilatory function and chronic mucus hypersecretion to death from lung cancer has been studied in 13,946 subjects randomly selected from the general population of the city of Copenhagen, Denmark. During the 10-yr follow-up, 225 subjects died from lung cancer. Percent predicted FEV1 (%FEV1) and presence of chronic phlegm were used to characterize ventilatory function and chronic mucus hypersecretion, respectively. Mortality analysis employed the multiple regression model of Cox and included age, sex, pack-years of smoking, and inhalation as confounding factors. %FEV1 and chronic phlegm were found to be significant predictors of death from lung cancer. In both men and women with chronic phlegm, the risk of dying from lung cancer was 1.5 greater than in those without phlegm. Compared with subjects with %FEV1 greater than or equal to 80, the subjects with %FEV1 less than 40 and those with %FEV1 between 40 and 79 had a 3.9 and 2.1 higher risk of lung cancer death, respectively. A similar regression model in which %FEV1 was replaced with the ratio of FEV1 to FVC (FEV1/FVC) showed that lowered FEV1/FVC was also a significant predictor of lung cancer death, the subjects with FEV1/FVC less than 0.6 (0.6 to 0.7) having a 2.6 (1.5) higher risk for lung cancer death than those with FEV1/FVC greater than or equal to 0.7. It is concluded that lowered ventilatory function and chronic mucus hypersecretion are both significant predictors of death from lung cancer, even after standardization for smoking.