Detection of Mycobacterium Tuberculosis Resistance to Rifampicin and Isoniazid by Nitrate Reductase Assay.The purpose of this study was evaluation of the nitrate reductase assay method as a rapid, sensitive and inexpensive drug susceptibility test for detecting rifampicin and isonaizid resistant myobacterial tuberculosis in comparison to conventional proportion method. This test was performed indirectly after isolating M. tuberculosis on Lowenstein-Jensen media.This study proves that the Nitrate reductase assay is a rapid test of high accuracy and could be an alternative to conventional proportion method in detection of rifampicin and isonaizid resistant M. tuberculosis.