This study will evaluate patient quality of life and tolerability of a HAART (highly active antiretroviral therapy) regimen containing twice-daily subcutaneous injections of Fuzeon in clinically stable, treatment-experienced patients with HIV-1 infection. All patients will use a 31-gauge thin-walled 8mm needle to administer Fuzeon. The anticipated time on study treatment is 3-12 months, and the target sample size is 100-500 individuals.

Inclusion Criteria:

• adults or adolescents at least 16 years of age;
• HIV-1 infection;
• clinically stable, treatment-experienced;
• evidence of HIV-1 replication despite ongoing antiretroviral therapy;
• CD4 + count greater than 50 cells/mm3.

Exclusion Criteria:

• previous use of Fuzeon and/or T-1249;
• active, untreated opportunistic infection;
• inability to self-inject, unless a reliable caregiver is available to inject.