INCLUSION CRITERIA:

To be eligible for this trial, patients must fulfill all inclusion criteria listed below:

1. Male and female HIV-1 infected adults or adolescents (greater than or equal to 16 years of age).
2. CD4 lymphocyte count less than or equal to 100 cells/mm(3) and HIV-1 RNA viral load greater than or equal to 10,000 copies/mL while on HAART (latest available measurement must be within the last 90 days).
3. Patients must be limited by the current commercially available antiretroviral agents or agents available via Early Access or Compassionate Use Programs as per the judgment of the investigator OR patients with advanced disease and most in need defined as prior documented drug resistance or have documented evidence of greater than 6 months prior experience to each of the three classes of ARV's.
4. Patients must be able and willing to provide written informed consent (for patients less than 18 years of age, a parent or legal guardian must also sign the Informed Consent Form).
5. Women of childbearing potential must have a documented negative pregnancy test at baseline and ensure that two reliable forms of contraception are being used, including a barrier method, for the duration of the study, and for 90 days after the last dose of study medication.

EXCLUSION CRITERIA:

Patients meeting any of the following exclusion criteria will not be eligible for participation in this trial:

1. Female patients who are pregnant, breast-feeding, or who plan to become pregnant or breast-feed during the study.
2. Any current clinical or laboratory parameter of ACTG grade 4. Asymptomatic grade 4 abnormalities will be permitted, at the discretion of the investigator, if the potential benefit of treatment outweighs the potential risk.
3. Evidence of ongoing alcohol and/or drug or substance abuse that, in the judgment of the investigator, would result in the patient being unreliable in fulfilling the conditions of this protocol.
4. Prior non-adherence to antiretroviral treatment regimens that, in the judgment of the investigator, resulted in the patient's failing prior regimens and which would likely result in the patient being unreliable in fulfilling the conditions of this protocol.
5. Inability to self-inject Fuzeon (enfuvirtide) as indicated in the protocol, unless a reliable caregiver is willing, able, and available to provide this service on a continuous basis for the duration of the study.
6. Evidence of active, untreated opportunistic infection, intercurrent illness, drug toxicity or any other condition such that, in the judgment of the investigator, the patient would not be able to continue or take a prescribed antiretroviral regimen.