Tuberculosis (TB) is the most important cause of infectious disease in the world, with eight million new cases and three million deaths each year. The increasing incidence of TB in the developed and the developing world, increasing drug resistance, and the occurrence of nosocomial outbreaks of drug sensitive as well as drug resistant TB has led the PHLS to establish TB as a priority area. This article reviews the enhanced reference services for mycobacteriology provided by the PHLS in England and Wales. These include microscopy and culture on solid and liquid media, rapid culture systems, identification of mycobacteria using macroscopic, microscopic, growth, and biochemical characteristics, and molecular DNA analysis. The Mycobacterium Reference Unit (MRU) provides rapid molecular DNA amplification techniques to identify Mycobacterium tuberculosis in specimens. All four PHLS Regional Centres test isolates for drug susceptibility. This work is quality controlled by MRU, which is one of the World Health Organisation's reference centres for global surveillance on drug resistance in tuberculosis. National data on drug resistance are collated through 'Mycobnet', a surveillance scheme run through the collaboration of PHLS and other UK reference centres and the PHLS Communicable Disease Surveillance Centre.