Combination antiretroviral therapy including two nucleoside reverse transcriptase inhibitors (NRTIs) and a single HIV-1 protease inhibitor (PI) results in significant and sustained decreases in plasma HIV-1 RNA with a resultant marked diminution in the selection of drug-resistant variants in those able to adhere to and tolerate these regimens. However, two lines of evidence suggest that additional and perhaps more aggressive approaches may be necessary in some HIV-infected individuals: 1) the failure of some potent three-drug regimens to sustain viral replication to levels below the limits of detection; and 2) the ability to recover virus from lymphoid tissue obtained from those without evidence of detectable plasma HIV-1 RNA using the most sensitive assays. A regimen containing more drugs with potentially different mechanisms of action or synergistic activity may result in greater, more rapid, or more durable antiviral activity, or reduce the number of latently infected cells in those patients with acute or early HIV-1 infection.