INCLUSION CRITERIA:

1. Documentation of HIV-1 infection by licensed ELISA test kit and confirmed by a second method (e.g. Western Blot).
2. Absolute CD4+ T-cell count of greater than or equal to 300/mm(3) within 30 days before randomization (For patients who are status post-splenectomy, also CD4+ T-cell greater than 20 percent)
3. Receiving HAART (at least an NNRTI or a PI and at least 3 drugs) with at least 1 viral load test below the limit of detection (at least less than 500 copies/ml) greater than or equal to 3 months before screening.
4. Stable HAART regimen greater than or equal to 1 month.
5. Two confirmatory viral loads of less than 50 copies/ml prior to enrollment.
6. Age at least 18 years.
7. For women of childbearing potential, a negative pregnancy test (serum or urine) is required within 14 days prior to treatment assignment.
8. Ability to inject, or willingness to have injected by another person, T20 as required by protocol.

9. Laboratory values (within 30 days prior to randomization):

   1. AST no more than 5 x the upper limit of normal (ULN).
   2. Total or direct bilirubin no more than 2 times ULN unless there is a pattern consistent with Gilbert's syndrome or the patient is receiving indinavir.
   3. Creatinine no more than 2.0 mg/dL.
   4. Platelet count at least 50,000/microliters.
10. Willingness to provide blood samples for storage that may be used in future studies of HIV infection and/or immunopathogenesis.

EXCLUSION CRITERIA:

1. Concurrent malignancy, or any other disease state, requiring cytotoxic chemotherapy.
2. Symptomatic for significant HIV-related illnesses, such as opportunistic infections and malignancies other than mucocutaneous Kaposi's sarcoma.
3. A history of receiving both an NNRTI and a PI.
4. Use of experimental, unlicensed antiretrovirals less than or equal to 6 months prior to enrollment. An exception may be made for hydroxyurea according to the judgement of the Principal Investigator.
5. Current use of IL-2 or abacavir or prior participation in a HAART interruption study.
6. Pregnancy or breastfeeding during study period.
7. Significant cardiac, pulmonary, kidney, rheumatologic, gastrointestinal, or CNS disease as detectable on routine history, physical examination , or screening laboratory studies.
8. Psychiatric illness that, in the opinion of the PI, might interfere with study compliance.
9. Active substance abuse or history of prior substance abuse that may interfere with protocol compliance or compromise patient safety.
10. Refusal to practice safe sex or use precautions against pregnancy (effective birth control or abstinence).
11. Known history or laboratory evidence of chronic hepatitis B infection requiring 3TC for control including surface antigen positivity.
12. Receiving salvage HAART, i.e. evidence of clinical resistance to licensed antiretrovirals.

Individuals accepted into the protocol who subsequently violate exclusion criteria 7-9 will be offered further counseling and psychiatric evaluation if indicated. If the situation is not resolved within a reasonable period of time, the PI, in consultation with the care team, may terminate subject participation.