EAP charts from patients at the study sites who meet the inclusion criteria will be reviewed and data abstracted. A comparison of the response to treatment by viral load measurement with raltegravir will be compared in patients whose regimens contained a protease inhibitor (PI) with those that did not contain a PI. Other endpoints will also be assessed including percent of patients with viral loads less than 400 copies/ml, less than 50 copies/ ml, CD4 cell changes, consequences of failure of raltegravir and use of predictive parameters such as GSS and PSS.