Background HIV is a risk factor for empyema. HIV-infected patients with empyema appear to have worse outcomes. This study assessed whether HIV infection affected aetiology or outcomes of patients with empyema. Methods A retrospective study of patients with empyema admitted to CHBAH from January 2006 to December 2009 was conducted. HIV-infected and non-infected patients were evaluated for differences in aetiology and outcomes. Sub-analysis according to CD4 counts and antiretroviral use in HIV-infected patients was performed. Results 0f 172 patients, 125 (73%) were HIV-infected. HIV infected patients with lower CD4 counts were more often diagnosed with clinical tuberculosis (p<0.05). Aetiology of empyema was frequently not determined in HIV non-infected patients (p<0.05). More patients on antiretrovirals underwent thoracic surgery (p<0.05) and had shorter hospital stays than those not on antiretrovirals (p<0.05). Conclusions No differences in empyema aetiology among HIV-infected versus non-infected patients were found. Antiretroviral use was associated with improved outcomes.