We assessed the safety and efficacy and evaluated the adherence to lopinavir/ritonavir (LPV/r) dosed QD or BID in antiretroviral-naive, HIV-1-infected subjects through 96 weeks of treatment. A randomized, open-label, multicenter comparative study was conducted. A total of 190 antiretroviral-naive subjects with plasma HIV-1 RNA above 1000 copies/ml and any CD4(+) T cell count were enrolled. Subjects were randomized (3:2) to LPV/r 800/200 mg QD (n = 115) or 400/100 mg BID (n = 75). Subjects received TDF 300 mg and FTC 200 mg QD. Adherence to LPV/r through 96 weeks was measured using MEMS((R)) monitors. Median baseline VL and CD4(+) T cell count were 4.8 log(10) copies/ml and 216 cells/mm(3), respectively. Prior to week 96, 37% (QD) and 39% (BID) of subjects discontinued, primarily due either to adverse events (17% QD, 9% BID) or to loss to follow-up or nonadherence (12% QD, 17% BID). The proportion of subjects with VL <50 copies/ml [57% QD, 53% BID; p = 0.582 (ITT NC = F)], change in CD4 count (244 cells/mm(3) QD, 264 cells/mm(3) BID; p = 0.513), and evolution of resistance did not differ between groups through 96 weeks. Diarrhea (17% QD, 5% BID, p = 0.014) was the most common moderate or severe, study drug-related adverse event. Adherence to LPV/r was higher for the QD group than the BID group and declined over time in both groups. Time to loss of virologic response was significantly associated with adherence to LPV/r in both groups. LPV/r QD resulted in virologic response similar to LPV/r BID through 96 weeks in antiretroviral-naive subjects. Adherence was significantly higher in the QD group.