HIV-1 RT and protease sequencing and drug susceptibility testing have been done in research settings for more than ten years to elucidate the genetic mechanisms of resistance to antiretroviral drugs. The accumulation of retrospective and prospective data has led expert panels to recommend the use of resistance testing in the decision of treatment of HIV-infected patients. The French ANRS (National Agency for AIDS Research) AC11 Resistance group provides HIV-1 genotypic drug resistance interpretation’s algorithms in order to guide physicians in the choice of antiretroviral treatment.These algorithms are mainly based on correlation between drug resistance mutations and virological outcome from patients failing antiretroviral therapy. The rules are presented as tables listing mutations conferring genotypic resistance or possible genotypic resistance to anti-HIV drugs and will be updated regularly.