 Despite the advent of highly active antiretroviral therapy HAART, many HIV infected patients without access to antiretroviral therapy ART present with acute OIs. Such presentations pose a management problem, as there are currently no data available as to whether initiating HAART during the acute presentation is of benefit. Reports of an immune reconstitution inflammatory syndrome IRIS marked by increasing hypoxia or new pulmonary infiltrates have been associated with the initiation of ART in patients with AIDS. There is also concern as to drug interactions between ART and antimicrobials used to treat the presenting OI. This study will evaluate the possible benefits and costs of initiating ART in HIV infected patients who present with an AIDS-defining OI. 