In this study, resistance rates of 125 M.tuberculosis strains isolated in Zonguldak between 2003-2005, to primary antituberculosis drups were determined by BACTEC MGIT 960 system. While 87 (69, 6 %) of the isolates were susceptible to all of the drugs tested, 38 (30, 4%) were resistant to at least one drug and four (3, 2%) were resistant to all of the drugs. Of the isolates tested, 19.2%, 23.2%, 8.0% and 4.0% were resistant to streptomycine, isoniazide, rifampicine and ethambutole, respectively. Eight percent of the isolates were multiple-drug resistant. The primary resistance rates for streptomycine, isoniazide, rifampicine and ethambutole were found as 13.1 %, 18.2%, 2.0% and 3.0%, respectively while secondary resistance rates for the same drugs were 50.0%, 42.9 %, 35.7% and %14.3, respectively. The rate of multiple drug resistance was 2% in new cases while it was 35, 7% in patients with the history of previous antituberculosis treatment. Of all the isolates, 10 (8%) were resistant to two drugs while four (3, 2%) were resistant to three drugs and four (3, 2%) were resistant to four drugs. Eight ısolates were only streptomycine resistant (6.4 %) and 12 isolates were only izoniazid resistant (9.6 %) while there were no isolates resistant to only rifampicine or ethambutole.