Objective To investigate the resistant patterns of Mycobacterium tuberculosis (MTB) strains against first- and second-line anti-tuberculosis drugs. Methods Drug susceptibility tests of 518 MTB strains collected from January 2008 to March 2009 were performed using BactecMGIT 960. The data were analyzed by chi square test. ResultsIn 518 strains, 168 (32.44％) were all sensitive to all seven drugs, 350 (67.56％) were resistant to at least one drug. Among all strains, 72 (13.90％) were resistant to one drug, 24 (4.63％) were resistant to two drugs, 254 (49.03％) were resistant to three or more drugs. A total of 217 strains (41.89 ％) were classified as multi-drug resistant tuberculosis (MDR-TB)strains and 65(12.55％)were extensively drug resistant tuberculosis (XDR-TB) strains which accounted for 29.95 ％ of MDR-TB strains. The drug resistant rate of isoniazid which belonged to first-line drugs was 53.67％ (278 strains) and that of ofloxacin which belonged to second-line drugs was 39.77 ％ (206 strains). In 433 retreated patients, the drug resistant rate against any drugs, MDR rate and XDR rate were 72.05％, 46.42％ and 13.86％,respectively, which were all higher than those in treatment naive patients (44.70％, 18. 82％ and 5.88％, respectively; x2 = 24. 253, x2 ＝ 22. 229 and x2 ＝ 4. 117, respectively; all P ＜ 0.01).ConclusionsThe resistant rate of MTB is high in a tuberculosis specialized hospital in Shanghai, and MDR-TB also shares a high resistant rate as well as XDR-TB. Furthermore, drug resistance is more common in retreated patients.