Therapeutic options for treatment-experienced HIV-infected patients have been limited. The DUET trial evaluated the use of etravirine, a second-generation non-nucleoside reverse transcriptase inhibitor (NNRTI), or placebo, in 1203 treatment-experienced, HIV-infected patients. Eligible patients had to have evidence of NNRTI and protease inhibitor resistance-associated mutations, and evidence of virologic failure, as defined as a plasma viral load > 5000 copies/ml on antiretroviral therapy at the time of screening. Patients in both arms received an optimized background regimen including darunavir/ritonavir. DUET demonstrated superior outcomes in virologic suppression (plasma viral load < 50 copies/ml) and clinical end points including new AIDS-defining illnesses and death, in those randomized to receive etravirine. These results were maintained at 48 weeks of follow-up. Furthermore, etravirine was shown to be safe and well-tolerated over this period. In exploratory analyses, patients in the DUET study with greater number of active agents within the background regimen were more likely to have a fully suppressive response. Taken together, the DUET results highlight the high rates of virological success that can be achieved using new active agents, such as ritonavir-boosted darunavir and etravirine, in treatment-experienced patients with underlying drug-resistant HIV infection.