An increasing number of patients are developing multidrug-resistant (MDR) virus, as determined by genotypic antiretroviral resistance testing (GART), due to treatment failure to suppress viral replication after several rounds of combination antiretroviral therapy. The best therapeutic strategy for these patients is uncertain. Two strategies currently being used are (1) STI followed by a new antiretroviral regimen and (2) immediate initiation of a new antiretroviral regimen.