Efavirenz (DMP-266, Sustiva, Stocrin) is a member of the non-nucleoside class of HIV-1 reverse transcriptase inhibitors. It has demonstrated potent antiretroviral activity in treatment-naïve patients in combination with two nucleoside analogues or with a protease inhibitor. In nucleoside analogue-experienced patients, best activity has been seen with two nucleosides plus a protease inhibitor. An open-label comparison versus indinavir plus two nucleoside analogues in predominantly treatment-naïve patients, demonstrated that the efavirenz-based triple therapy provides at least similar antiviral effects, and possibly stronger effects, over 48 weeks. Furthermore, fewer patients discontinued efavirenz-based triple therapy than indinavir-based therapy because of adverse events. Side-effects associated with efavirenz include a maculopapular rash and central nervous system (CNS) disturbances (dizziness, vivid dreams, poor concentration, sleep disturbances) which generally occur, and resolve, within the first weeks of therapy. Efavirenz will be used as a combination agent with other antiretrovirals where therapy for HIV infection is indicated.