While indinavir is currently the most commonly prescribed protease inhibitor, the optimal therapy for a person on an indinavir-containing regimen who experiences a rebound in viral load or never experiences a decrease in viral load below 500 copies per milliliter is unknown. Current clinical practice for such patients typically involves empiric use of a combination of other protease inhibitors (saquinavir/nelfinavir or saquinavir/ritonavir) and at least 1 other antiretroviral agent to which the patient has had little or no prior exposure. This may involve the use of 1 or more reverse transcriptase inhibitors (RTIs) or nonnucleoside reverse transcriptase inhibitors (NNRTIs). This study attempts to formally evaluate some of these options in indinavir-experienced patients.