In most studies, people who have not responded virologically to a protease inhibitor (PI)-containing regimen have tended to experience poor virologic responses to subsequent regimens. We describe the 2-year viral load, CD4 count, and clinical outcome of a multidrug regimen used in 60 people who had not responded virologically to a PI-containing regimen. At baseline, median CD4 count was 126/mm3(nadir 30/mm3) and median viral load was 320,000 copies/mL. A median of five antiretroviral drugs had previously been used, of which a median of two were PIs. Of these patients, 16% had previously used another nonnucleoside reverse transcriptase inhibitor besides efavirenz. The multidrug regimen (median 5 drugs) started most commonly included efavirenz (100%), at least one PI (92%, usually indinavir/ritonavir), didanosine (78%), and hydroxyurea (74%). At year 2, 5 patients had died and 5 had no measure available. Nine patients developed a new AIDS event and 10 patients were known to have stopped all antiretroviral therapy. Thirty-one patients (52% of the whole group, 72% of those remaining on therapy with viral load value available) had viral load <50 copies/mL. Thus, a substantial proportion of patients who had failed to respond virologically to PI-containing regimens can achieve profound and sustained virologic suppression with a multidrug regimen.