The combinations of two or more anti retroviral drugs have synergistic
activity against HIV and prevent the emergence of HIV-nucleosides res
istant isolates. Results of some recent in vitro studies have not yet
been confirmed by clinical studies but the conclusions of two main stu
dies (ACTG 175 in USA and DELTA in Europe) are awaited. HIV resistance
, potential benefits of nucleosides combinations and results of clinic
al studies are discussed.