Tuberculosis is an important infection threatening public health. Th e aim of our study was to determine the resistance rate of Mycobacterium tuberculosis complex strains to four major antituberculosis drugs. 3746 samples suspected of tuberculosis were sent to the Microbiology Laboratory of Gaziantep University Hospital between January 2007 and December 2008. Th e samples were cultured using BACTEC MGIT 960 (Mycobacteria Growth Indicator Tube, Becton Dickinson, USA) tuberculosis culture system. Susceptibility of mycobacteria to major antituberculosis drugs such as streptomycin (STR), isoniasid (INH), rifampicin (RIF) and ethambutol (EMB) were determined by using the same method. 116 (3.09%) Mycobacteria belonging to M.tuberculosis complex group, 9 (0.24%) MOTT bacilli, 1 (0.02%) Nocardia spp. were isolated from the samples obtained from patients. Out of 116 M. tuberculosis complex strains, 74 were isolated from sputum, 26 from (22.4%) bronchoalveolar lavage, 4 (3.4%) pleura, 3 (2.6%) from cerebrospinal fluid, 3 (2.6%) from operation material–biopsy, 2 (1.7%) abscess, 2 (1.7%) from lymph gland, 1(0.9%) from pus and 1 (0.9%) from urine samples. 85 (73.3%) of these strains were found susceptible to four agents tested; however, resistance to one or more drugs was observed in 31 (26.7%) strains. Of the resistance determined strains, 22 (19%) strains were found to be resistant to one drug, 8 (6.9%) strains to two drugs, one (0.8%) strain to the tested four drugs. Th e highest level of drug resistance was determined in 10 (8.6%) strains, which were found to be resistant to INH. Control and evaluation of drug resistance patterns of M. tuberculosis strains to major drugs over fixed period of time will help us be informed on number of patients and resistance states and take necessary precautions.