Tuberculous pleural effusions occur in up to 30% of patients with tuberculosis. It appears that the percentage of patients with pleural effusion is comparable in human immunodeficiency virus (HIV)-positive and HIV-negative individuals, although there is some evidence that HIV-positive patients with CD4+ counts <200 cells x mL(-1) are less likely to have a tuberculous pleural effusion. There has recently been a considerable amount of research dealing with the immunology of tuberculous pleurisy. At present, we have more evidence that activated cells produce cytokines in a complex pleural response to mycobacteria. Intramacrophage elimination of mycobacterial antigens, granuloma formation, direct neutralization of mycobacteria and fibrosis are the main facets of this reaction. With respect to diagnosis, adenosine deaminase and interferon gamma in pleural fluid have proved to be useful tests. Detection of mycobacterial deoxyribonucleic acid (DNA) by the polymerase chain reaction is an interesting test, but its usefulness in the diagnosis of tuberculous pleurisy needs further confirmation. The recommended treatment for tuberculous pleurisy is a 6 month regimen of isoniazid and rifampicin, with the addition of pyrazinamide in the first 2 months. HIV patients may require a longer treatment. The general use of corticosteroids is not recommended at this time, but they can be used in individuals who are markedly symptomatic.