The ARTEMIS study compared the efficacy of darunavir/ritonavir at once-daily doses of 800/100 mg versus once- or twice-daily doses of lopinavir/ritonavir, together with 300 mg of tenofovir and 200 mg of emtricitabine, both in once-daily doses, in treatment-naive patients. The results at 48 weeks show that darunavir/ritonavir is not inferior to lopinavir/ritonavir; the increase in CD4 count observed with both regimens was similar. Darunavir/ritonavir was superior to lopinavir/ritonavir in patients with high viral loads (>100,000 copies/mL). The use of darunavir/ritonavir was associated with a lower proportion of grades 2-4 adverse effects, especially gastrointestinal effects such as diarrhea and with a lower frequency of lipidic adverse effects, such as increased triglyceride and total cholesterol levels. Once-daily darunavir/ritonavir may be an option in first-line antiretroviral therapy, with the added advantage of a reduced dose of ritonavir and high efficacy in patients with elevated viral loads.