The risk factors for lung cancer in lifetime nonsmoking women were investigated in a hospital-based case-control study in the urban area of Shenyang, China, between April 1992 and May 1994. One-hundred thirty-five newly-diagnosed lung cancer cases and an equal number of controls, matched for age and sex, were enrolled and interviewed by trained personnel who administered a standardized questionnaire. The histopathological cell type was predominantly adenocarcinoma (54.5%), followed by small cell carcinoma (20%), squamous cell carcinoma (16.4%), and others (9.1%). The data were analyzed using the Mantel-Haenszel method and by multivariate logistic regression analysis. The odds ratio (OR) and confidence interval (CI) associated with cooking oil vapors and with family history of cancer were 3.79 (95% CI, 2.29-6.27) and 2.29 (95% CI, 1.01-5.17), respectively. No association was found between exposure to environmental tobacco smoke (ETS), presence of previous lung diseases, and "kang" use. Cooking practices, exposure to cooking fumes, and a family history of cancer were found to significantly increase the risk of lung cancer.