Multidrug-resistant tuberculosis (MDR-TB), defined as TB caused by organisms that are resistant to isoniazid and rifampicin, two first-line anti- TB drugs, continues to threaten the progress made in controlling the disease. The emergence of extensively drug-resistant TB (XDR-TB), defined as MDR-TB that is resistant as well to any one of the fluoroquinolones and to at least one of three injectable second-line drugs (amikacin, capreomycin or kanamycin), has heightened this threat. XDR-TB has been identified in all regions of the world since 2006. Treatment outcomes are significantly worse in XDR-TB patients than in MDR-TB patients. Outbreaks of XDRTB in populations with high prevalence of HIV have caused alarmingly high mortality rates. The emergence of XDR-TB as a new threat to global public health demands that health officials and health-care providers respond with a coordinated strategy drawing on the Stop TB Strategy. Guidelines for the programmatic management of drug-resistant tuberculosis: emergency update 2008 provides updated guidelines and recommendations on how to manage drug-resistant TB (DR-TB) based on a rapid assessment of the best available evidence by a group of experts. A fully revised second edition will be published in 2010, following WHO guidance on retrieval, synthesis and grading of evidence. Until that time, the emergency update serves as interim guidance for TB control programmes and medical practitioners on all aspects of the management of DR-TB, including XDR-TB. It contains 19 chapters based on the original 18 chapters from the first edition published by the World Health Organization in 20062 plus an additional chapter on patient-centered care.