Clinical and Immunologic Monitoring of Patients With Known or Suspected HIV Infection

* INCLUSION CRITERIA: Patients are subject to selection by the Principal Investigator, and will satisfy all of the following inclusion criteria: 1. HIV-infection as documented by positive HIV ELISA and Western Blot or positive assay for HIV RNA (serum or plasma). Patients may also be included if they have laboratory or clinical evidence suggestive of possible HIV-infection. 2. Age 18 years or older. 3. Ability and willingness of subject to understand study requirements and give written informed consent. 4. Group I patients are required to have a primary care provider outside NIH to manage non-HIV medical problems. Group II patients must have a referring physician or clinic that will continue to manage HIV and non-HIV medical care. 5. For Group I patients, residence within the greater Washington DC area (approximately within a 100-mile radius of the NIH Bethesda campus) is required. EXCLUSION CRITERIA: A prospective study subject will be ineligible for this study if he or she satisfies either of the following criteria: 1. Has active drug or alcohol use or dependence or any other condition that, in the opinion of the investigator, would interfere with adherence to study requirements. 2. Refuses to allow collection and storage of samples for research purposes.