Acquired Immunodeficiency Syndrome (AIDS) is no longer restricted to gay white men. Women, especially women of color, represent the most rapidly- growing segment of persons infected with HIV (human immunodeficiency virus). Despite the increasing frequency of HIV infection in women, virtually all the information available regarding the natural history of HIV infection and its effects on the lung is derived from studies of infected men. Recent reports suggest that important gender differences exist in the type and frequency of complications, particularly in regard to respiratory disease. In both genders in the general population, cigarette smoking represents the major preventable cause of respiratory morbidity and mortality, accelerating loss of lung function and predisposing to bacterial and other infections. In HIV-infected individuals, preliminary reports (again mainly in men) suggest that cigarette smoking may predispose to bacterial pneumonia and may worsen the pulmonary dysfunction which occurs after PCP. Based on these data, we hypothesize that cigarette smoking among HIV-infected women alters the spectrum, frequency, and severity of respiratory complications (both non- infectious and infectious) of HIV infection. Specifically, we surmise that in HIV-seropositive women, cigarette smoking increases airway hyperresponsiveness, accelerates the loss of lung function, and predisposes to the development of obstructive lung disease. Furthermore, we conjecture that cigarette smoking affects the type and extent of acute and chronic respiratory infections that these women experience. To test this hypothesis, we will assess respiratory health by lung function testing, by questionnaire and by surveillance for infectious complications over the course of a 3 year observation period in a cohort of HIV- seropositive women - representatively diverse in terms of race/ethnicity, HIV risk factors, socioeconomic status, and smoking exposure. For both non-infectious and infectious outcomes multiple regression analysis will be used to discern the relative importance of cigarette smoking as an independent risk for loss of lung function and infectious complications.