The emergence in 2006 of extensively drug-resistant strains of tuberculosis, especially in countries with a high prevalence of human immunodeficiency virus, are serious threats to global public health and jeopardizes efforts to effectively control the disease. These important developments and the availability of new evidence related to the diagnosis and management of drug-resistant tuberculosis have mandated an urgent update of existing guidelines. Guidelines for the programmatic management of drug-resistant tuberculosis: emergency updated edition 2008 replaces previous publications by the Wor