Tuberculosis is a serious opportunistic infection that may affect transplant recipients. The incidence of tuberculosis among such persons is 20-74 times higher than that for the general population, with a mortality rate of up to 30%. The most common form of acquisition of tuberculosis after transplantation is the reactivation of latent tuberculosis in patients with previous exposure. Clinical presentation is frequently atypical and diverse, with unsuspected and elusive sites of affection. Manifestations include fever of unknown origin and allograft dysfunction. Coinfection with other pathogens is not uncommon. New techniques, such as PCR and quantification of interferon- gamma , have been developed to achieve more-rapid and -accurate diagnoses. Treatment requires control of interactions between antituberculous drugs and immunosuppressive therapy. Prophylaxis against latent tuberculosis is the main approach to treatment, but many issues remain unsolved, because of the difficulty in identifying patients at risk (such as those with nonreactive purified protein derivative test results) and the toxicity of therapy.