The aim of the study is to verify the effect of HAART in critically ill HIV infected patients. The current practice is to begin antiviral therapy after ICU discharge, when the condition of the patient is more stable. The investigators hypothesis is that the investigators can improve outcome of these patients with earlier antiviral therapy in the ICU. The investigators just have retrospective studies in this scenario. After admission to ICU, patients are assigned to one of two arms: early HAART (within 5 days of ICU admission) or conventional therapy (initiation of HAART after ICU discharge). The following data will be collected: demographic variables, CD4 count, viral load, drug toxicity, opportunistic infection, hemodialysis, mechanical ventilation and vasoactive drug. The patients will be followed to determine ICU mortality, hospital mortality and 6-month mortality.