Purpose of the study Among the currently available antiretroviral drugs, the novel integrase inhibitor raltegravir (RAL) is an oral agent without cross-resistance to any other antiretroviral family and it provides an option with easier administration and better tolerability than enfuvirtide (ENF). There is no experience in routine clinical practice with RAL as a simplification strategy. We evaluate the efficacy and safety of switching ENF to RAL as a simplification strategy for a follow-up of 24 and 48 weeks in patients with an HIV-1 viral load (VL) < 50 copies/mL.