We evaluated the relation between forced expiratory volume in 1 second (FEV1) and lung cancer incidence and mortality among members of the Kaiser Permanente Medical Care Program who took a multiphasic health checkup. FEV1 was inversely related to risk of lung cancer among former and current smokers, but not related among never-smokers. We observed a decreased risk of lung cancer mortality only in the higher quintiles of FEV1 in current smokers among men, but not in women. FEV1 appears to be associated with lung cancer as a physiologic marker for smoking-induced pulmonary damage.