United States Army personnel who have been tested as seropositive for the Human Immunodeficiency Virus (HIV) will be given medical examinations and treatment at Walter Reed Army Medical Center (WRAMC). These subjects will also be given the opportunity to participate in a medical research protocol to study the natural history of HIV infection, administered by the Walter Reed Army Institute of Research (WRAIR - see attached protocol). An oral component has been developed by staff of the National Institute of Dental Research (NIDR) in collaboration with U.S. Army medical and dental staff at WRAMC and WRAIR. Under the existing WRAIR natural history portocol, the oral examination is limited to the identification of pseudomembranous candidiasis (thrush), hairy leukoplakia, and the detection of enlarged lymph nodes in the head and neck region. The addition of the oral component will permit documentation of the prevalence and incidence of the full range of oral conditions in relation to the stage of HIV infection and systemic disease. Risk factors associated with these conditions will also be characterized, and the role of oral manifestations as early predictors or markers of disease progression will be elucidated. Finally, the role of saliva in the transmission of the virus will be investigated.