Based on data from twenty-five antiretroviral naïve patients failing a fosamprenavir containing regimen (one of whom showed Baseline resistance to lopinavir and saquinavir and another to tipranavir the resistance pathways associated with amprenavir produce limited cross-resistance to atazanavir/ ritonavir (three of 25 isolates), darunavir/ ritonavir (four of 25 isolates), indinavir/ ritonavir (one of 25 isolates), lopinavir/ ritonavir (three of 24 isolates, saquinavir (three of 24 isolates) and tipranavir/ ritonavir (four of 24 isolates).