Respiratory problems continue to be a major burden of disease in HIV-infected patients, with more than 50% suffering at least one respiratory episode. In early HIV infection, respiratory infections are similar to those found in the general population, but more common. Progressive HIV-induced immunosuppression increases the risk of opportunistic infections and tumours. Highly active antiretroviral therapy (HAART) has reduced the incidence of HIV-associated opportunistic infections and tumours, but has had less impact on the incidence of bacterial pneumonia, tuberculosis and non-Hodgkin lymphoma. HAART may trigger immune phenomena including over-exuberant and uncontrolled immune response to exogenous antigen most commonly seen in Mycobacterium tuberculosis, where two 'syndromes' have been described: immune reconstitution inflammatory syndrome (IRIS) and 'unmasking' of asymptomatic, latent, indolent or incipient infection (ALI3). © 2009 Elsevier Ltd. All rights reserved.