No treatment is provided by this study, but patients will continue to receive highly active antiretroviral therapy (HAART) from other studies in which they are coenrolled. Blood and urine collection will occur at study entry and periodically throughout the study. Women may undergo pelvic exams and Pap smears. Portions of blood samples will be stored to evaluate genotypic/phenotypic susceptibility testing. Medical histories, physical exams, and questionnaires will be completed periodically.