A case-control study among white women in Los Angeles County was conducted to investigate the role of smoking and other factors in the etiology of lung cancer in women. A total of 149 patients with adenocarcinoma (ADC) and 71 patients with squamous cell carcinoma (SCC) of the lung and their age- and sex-matched controls were interviewed. Personal cigarette smoking accounted for almost all of SCC and about half of ADC in this study population. Among nonsmokers, slightly elevated relative risk(s) (RR) for ADC were observed for passive smoke exposure from spouse(s) [RR = 1.2; 95% confidence interval (Cl) = 0.5, 3.3] and at work (RR = 1.3; 95% Cl = 0.5, 3.3). Childhood pneumonia (RR = 2.7; 95% Cl = 1.1, 6.7) and childhood exposure to coal burning (RR = 2.3; 95% Cl = 1.0, 5.5) were additional risk factors for ADC. For both ADC and SCC, increased risks were associated with decreased intake of beta-carotene foods but not for total preformed vitamin A foods and vitamin supplements.