Lung cancer is the leading cause of cancer mortality in women worldwide. Although the rise and growing epidemic status of lung cancer are overwhelmingly attributed to tobacco use, its rank in nonsmokers as the seventh most common cause of cancer worldwide suggests that other factors contribute to this disease. The majority of lung cancers among nonsmokers occur in women. Aside from geographic, cultural, and genetic differences, hormonal and possibly infectious factors also may play etiologic roles. This review aims to discuss the epidemiology of lung cancer in women, as well as the incidence of second primaries, and presents current opinions on the myriad of causes.