In many parts of the world the commonest serious opportunistic infection that occurs in HIV-1 infected persons is tuberculosis (TB). HIV-1 co-infection modifies the natural history and clinical presentation, and adversely affects the outcome of TB. Severe disseminated disease is well-recognised but it is increasingly appreciated that early disease characterised by very few or no symptoms is also common. Immunodiagnostic methods to ascertain latent TB in HIV-1 infected persons are compromised in sensitivity. Chemoprevention of HIV-1-associated TB is effective, its benefits are restricted to those which have evidence of immune sensitisation and appear short-lived in areas of high TB burden. Although promising advances in the microbiological diagnosis of TB have recently occurred, the diagnosis of HIV-1-associated TB remains difficult because of more frequent presentation as sputum negative or extrapulmonary disease. Management of co-infected patients can be complex because of overlapping drug toxicities and interactions. Nevertheless consensus is developing that antiretroviral therapy should be provided as soon as practicable after starting TB treatment in HIV-1 co-infected persons. This has the consequence of increasing the frequency of immune reconstitution inflammatory syndrome, the pathogenesis and management of which is poorly defined.