This study will evaluate the signs and symptoms associated with Fuzeon injection (90mg sc) using the B2000 needle-free injection device, in HIV-1 positive patients experienced to Fuzeon treatment, but having difficulty tolerating long-term (>4 weeks) administration of Fuzeon with the standard needle and syringe. Patients will be randomized to the B2000 device or the standard needle and syringe for 4 weeks; all patients will use the B2000 device for the next 4 weeks. The anticipated time on study treatment is <3 months, and the target sample size is 100-500 individuals.

Inclusion Criteria:

• adult patients >=16 years of age;
• current or former Fuzeon user who may benefit from needle-free administration of Fuzeon;
• naive to use of the B2000 device;
• positive test results for human immunodeficiency virus infection.

Exclusion Criteria:

• patients naive to Fuzeon;
• inability to self-inject Fuzeon, or no reliable caregiver to administer injections;
• evidence of active, untreated, opportunistic infections.