Air travel provides opportunities for infectious diseases to spread rapidly between countries and continents. There may be a potential risk of transmission during the flight, notably with airborne and droplet-borne respiratory infections. Seven episodes of potential transmission of TB infection during air travel reported in 1992--1994 caused widespread concern. Contact investigations revealed evidence of transmission of infection in two instances but active TB disease was not found in any of the infected individuals, or in subsequently published cases. In recent years, multidrug-resistant TB (MDR-TB) has become an increasingly important public health problem in many countries, exacerbated by the emergence of extensively drug-resistant TB (XDR-TB). The potential risk of transmission of particularly dangerous forms of TB requires renewed vigilance. The revised International Health Regulations (1995) include new provisions which are relevant to the transmission of TB on aircraft. WHO published a second edition of Tuberculosis and air travel: guidelines for prevention and control in 2006, providing updated information and specific guidance for passengers and crew, physicians, public health authorities and airline companies. Following several recent incidents involving MDR-TB and XDR-TB in airline passengers, the 2006 recommendations will be amplified in the light of experience gained and the evolving epidemiological situation.