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.

Inclusion Criteria:

• HIV infection
• CD4 cell count less than 350 cells/mm3 within 3 months prior to study entry OR CD4 cell count between 350 cells/mm3 and 500 cells/mm3 if age > 55 years, coinfection with HBV or HCV, neoplasia, viral load > 100,000 copies/ml or elevated cardiovascular risk OR AIDS-defining illness

Exclusion Criteria:

• Regular use of HAART
• Pregnant