BACKGROUND The available information on the epidemic of drug-resistant tuberculosis in China is based on local or regional surveys.In 2007,we carried out a national survey of drug-resistant tuberculosis in China.METHODSWe estimated the proportion of tuberculosis cases in China that were resistant todrugs by means of cluster-randomized sampling of tuberculosis cases in the public health system and testing for resistance to the first-line antituberculosis drugs isoniazid,rifampin,ethambutol,and streptomycin and the second-line drugs ofloxacin and kanamycin.We used the results from this survey and published estimates of the incidence of tuberculosis to estimate the incidence of drug-resistant tuberculosis.Informarion from patient interviews was used to identify factors linked to drug resistance.RESULTS Among 3037 patients with new cases of tuberculosis and 892 with previously treated cases,5.7% (95% confidence interval [CI],4.5 to 7.0) and 25.6% (95% CI,21.5 to 29.8),respectively,had multidrug-resistant (MDR) tuberculosis (defined as disease that was resistant to at least isoniazid and rifampin).Among all patients with tuberculosis,approximately 1 of 4 had disease that was resistant to isoniazid,rifampin,or both,and 1 of 10 had MDR tuberculosis.Approximately 8% of the patients with MDR tuberculosis had extensively drug-resistant (XDR) tuberculosis (defined as disease that was resistant to at least isoniazid,rifampin,ofloxacin,and kanamycin).In 2007,there were 110,000 incident cases (95% CI,97,000 to 130,000) of MDR tuberculosis and 8200 incident cases (95% CI,7200 to 9700) of XDR tuberculosis.Most cases of MDR and XDR tuberculosis resulted from primary transmission.Patients with multiple previous treatments who had received their last treatment in a tuberculosis hospital had the highest risk of MDR tuberculosis (adjusted odds ratio,13.3; 95% CI,3.9 to 46.0).Among 226 previously treated patients with MDR tuberculosis,43.8% had not completed their last treatment; most had been treated in the hospital system.Among those who had completed treatment,tuberculosis developed again in most of the patients after their treatment in the public health system.CONCLUSIONS China has a serious epidemic of drug-resistant tuberculosis.MDR tuberculosis is linked to inadequate treatment in both the public health system and the hospital system,especially tuberculosis hospitals; however,primary transmission accounts for most cases.(Funded by the Chinese Ministry of Health.)