In the TORO, RESIST and POWER trials, the HIV-RNA < 50 copy endpoint showed the strongest durability over time, whereas HIV-RNA reductions of more than 1 log10 or below 400 copies/ml were less sustained during 48 weeks of treatment. Clinical trials of new antiretroviral drugs in highly experienced patients also show high rates of HIV-RNA suppression below 50 copies/ml. HIV-RNA suppression below 50 copies/ml should now become the standard efficacy endpoint across trials of both naive and experienced patients.