BACKGROUND: The aim of this study was to assess the long-term efficacy and safety of first-line treatment with once-daily saquinavir/ritonavir plus two nucleoside reverse transcriptase inhibitors (NRTIs). METHODS: A total of 272 antiretroviral-naive patients with a CD4+ T-cell count of 200-350 cells/mm3 were treated with two NRTIs and saquinavir/ritonavir 1,600/100 mg per day for > 24 weeks. Patients were followed up every 12 weeks for CD4+ T-cell counts, HIV RNA levels, clinical and laboratory toxicities. Intention-to-treat analyses were used for the first 24 weeks of treatment and as-treated analysis after week 24. RESULTS: The median baseline CD4+ T-cell count was 269 cells/mm3 and HIV RNA was 4.7 log10 copies/ml. At a median follow-up time of 56 (interquartile range [IQR] 25-113) weeks, 262/272 (96.3%) had HIV RNA < 400 copies/ml, with a median HIV RNA decline of -2.89 (IQR 3.31--2.37) log10 copies/ml (P < 0.001) and a median rise in CD4+ T-cell count of 192 (IQR 117-317) cells (P < 0.001). At weeks 24, 48, 72 and 96, 249/272 (91.5%), 157/164 (95.7%), 113/126 (89.7%) and 84/90 (93.3%) had HIV RNA < 400 copies/ml, respectively; at the same time points, 83.8%, 92.7%, 85.7% and 85.6% had HIV RNA < 50 copies/ml. Drug-related adverse events were reported in 6.30%. Significant rises in total cholesterol, triglyceride, low-density lipoprotein and high-density lipoprotein were seen. CONCLUSION: First-line highly active antiretroviral therapy with once-daily saquinavir/ritonavir plus two NRTIs showed strong antiviral efficacy.