Inclusion Criteria

Patients may be eligible for this study if they:

• Are HIV-positive.
• Have been taking anti-HIV therapy that includes at least 3 anti-HIV drugs and is an acceptable anti-HIV drug combination for 60 to 104 days before study treatment. Patients must not have changed any of the drugs in the 28 days before study entry. (This study has been changed by extending the number of days that anti-HIV therapy has been received.)
• Have a viral load greater than 500 but less than or equal to 10,000 copies/ml and have had a significant decrease in viral load between 49 and 84 days after starting this anti-HIV therapy. (This study has been changed by extending the length of time of viral load decrease.)
• Are at least 13 years old (consent of parent or guardian required if under 18).
• Agree to practice abstinence or use barrier method of birth control (such as condoms) during the study and for 3 months after.

Exclusion Criteria

Patients will not be eligible for this study if they:

• Have ever taken ABC.
• Have received anti-HIV therapy for more than 104 days in the past. (This study has been changed by extending the number of days that anti-HIV therapy has been received.)
• Have a fever for 7 days in the 30 days before study entry.
• Have cancer, including Kaposi's sarcoma, that requires chemotherapy.
• Have an active infection that requires treatment in the 21 days before study entry.
• Have any opportunistic (AIDS-related) infection or disease that requires a change in medication in the 14 days before study entry.
• Have any medical condition or history of an illness that the doctor feels would place them at risk or make them unable to complete the study.
• Are taking drugs that affect the immune system or any experimental anti-HIV drugs, except for their current drug combination.
• Are taking St. John's wort. (This study has been changed. Previously, patients taking St. John's wort were eligible.)
• Have received a vaccine in the 21 days before study entry.
• Are pregnant or breast-feeding.