A new formulation combining fixed doses of the nucleoside reverse transcriptase inhibitors emtricitabine (200mg) and tenofovir disoproxil fumarate (tenofovir DF; 300 mg) with the non-nucleoside reverse transcriptase inhibitor efavirenz (600 mg) represents the first once-daily, one-tablet antiretroviral regimen. Co-formulated efavirenz/emtricitabine/tenofovir DF demonstrated bioequivalence to concomitant administration of the individual agents in a pharmacokinetic trial in healthy volunteers (n = 48). Co-formulated efavirenz/emtricitabine/tenofovir DF has not been evaluated in clinical trials. However, a once-daily regimen of efavirenz, emtricitabine and tenofovir DF (administered as individual agents) was superior to once-daily efavirenz plus twice-daily co-formulated lamivudine/zidovudine in terms of virological suppression, immunological recovery and adverse events resulting in discontinuation of the study medications in a randomised, multicentre, noninferiority study in treatment-naive patients with HIV infection (n = 517). Both regimens are currently recommended as initial antiretroviral therapy. Preliminary data suggest that co-formulated efavirenz/emtricitabine/tenofovir DF, like the individual agents in combination with other antiretroviral drugs, is generally well tolerated. CNS adverse events, primarily headache and dizziness, were the most common treatment-emergent, drug-related adverse events in the pharmacokinetic study involving the co-formulation.