Objective:To analyze the drug susceptibility of M.tuberculosis isolates from suspected multidrug-resistant tuberculosis (MDR-TB) patients in Chongqing,so as to provide scientific evidence for MDR-TB discovery and control. Methods:Totally 573 M.tuberculosis isolates from suspected MDR-TB patients were collected from July 2014 to February 2016. Four kinds of first-line anti-TB drugs(INH,RFP,Sm,EMB) and six kinds of second-line drugs(Ofx,Km,Cm,Pto,PAS,Am) were tested for susceptibility by the proportion method. Results:Among the 573 suspected MDR-TB cases,143 cases(25.0%) were identified as MDR-TB,mean-while,55 cases(9.6%) were single drug-resistant tuberculosis(SDR-TB) and 46 cases(8.0%) were poly drug-resistant tuberculosis(PDR-TB). The proportion of MDR-TB was significantly higher than that of SDR-TB and PDR-TB(P<0.001). In terms of MDR-TB,the high risk groups had a higher drug resistance rate(26.6%,130/488) than the new patients(15.3%,13/85),P=0.026. Among the high risk groups,the detection rate of MDR-TB was the highest(42.1%,16/38) in the patients who failed in the re-treatment,fol-lowed by those failed in the initial treatment(40.0%,18/45). Conclusion:The detection rate of MDR-TB is moderately high among the suspected MDR-TB patients in Chongqing. A long way remained to go in controlling MDR-TB. The screening for MDR-TB should target at high risk groups especially the patients failed in the re-treatment and initial treatment.