Drug-resistant tuberculosis is a threat not only to the estimated 50 million people in the world carrying resistant strains, but also to the success of national TB control programmes. In Sweden, multidrug-resistant (MDR) tuberculosis comprises around 1% of the isolated strains. Isoniazid resistance is found in 7% of strains and resistance to other drugs in < 3%. Of patients with resistant TB 70% are born outside Scandinavia. Preliminary data from Estonia show that close to 20% of the strains are resistant to each of the drugs isoniazid, rifampicin and streptomycin. MDR is seen in around 16%. In a study in Ethiopia isoniazid resistance was found in 46% and MDR in 11% among treatment failures and relapse cases.