This is the third report of the WHO/IUATLD project which gives comparable worldwide information on anti-tuberculosis drug resistance, with data from surveys conducted in 77 different countries or geographical settings during the years 1999 to 2002. Global surveillance identifies areas of high resistance and draws the attention of national authorities to address the problems involved. The report also highlights the importance of conducting surveillance on re-treatment cases, and the role of the laboratory in TB control.