Highly active antiretroviral therapy (HAART) has made a significant impact on the natural history of HIV-1 infection, but toxicities and complexities of therapy limit long-term efficacy, and make simpler yet effective HAART regimens highly desirable. Previous attempts to 'de-intensify' protease inhibitor (PI)-based therapy by discontinuing reverse transcriptase inhibitors (RTI) after achieving viral suppression met with failure, probably because plasma levels of most individually administered PI are too low to inhibit viral replication consistently.