Patients take IDV plus RTV plus d4T plus 3TC twice daily for 24 weeks. Every 4 weeks, patients have physical exams and laboratory tests of blood and urine, and CD4 cell counts and plasma viral RNA are measured. At Week 24, the proportion of patients with plasma viral RNA below 400 copies/ml is determined to identify any clinically meaningful antiretroviral activity for the drug regimen. An observed response proportion of 80% or higher will be considered clinically meaningful.

Inclusion Criteria

Patients may be eligible for this study if they:

• Are HIV-positive.
• Have a CD4 cell count of 75 cells/mm3 or more and a viral load of 5,000 copies/ml or more.
• Are age 16 or older (consent of a parent or guardian required if under 18).
• Agree to practice abstinence or use barrier methods of birth control (such as condoms).
• Are willing to stop taking all anti-HIV drugs except study drugs. (Patients may be able to continue taking drugs for other infections.)

Exclusion Criteria

Patients will not be eligible for this study if they:

• Have cancer, lung disease, severe hepatitis, or active AIDS-related infections. (Certain AIDS-related infections such as Kaposi's sarcoma may be allowed).
• Have ever taken 3TC, abacavir (ABC), or a protease inhibitor (such as IDV or RTV).
• Have changed their medications in the last 2 weeks.
• Are allergic to IDV, RTV, d4T, or 3TC.
• Have used certain medications (see the technical summary for more detail).
• Are pregnant or breast-feeding.