Emergence of multidrug resistant tuberculosis (MDR-TB) and extensively drug resistant tuberculosis (XDR-TB) is one of the reasons why tuberculosis (TB) continues to cause great mortality and morbidity in less-developed countries. The development of rapid diagnostic methods targeting genetic mutations associated with resistance to the anti-tuberculous drugs is essential to fight this deadly pathogen. Isoniazid (INH) has been included in the multidrug regimens for the treatment of drug-susceptible TB for the decades. In the worldwide setting, isoniazid resistance was highly prevalent and was observed in one of every seven TB cases. Since katG315 mutation is highly prevalent, the common mutation in the enzyme essential for the activation of the INH concerned with the mechanism of drug resistance and associated with high level resistance to INH, katG315 mutation was necessary to be identified by molecular method as a molecular determinant of INH resistant Mycobacterium tuberculosis. The prevalence of katG315 mutation in various countries was discussed in this report and a new molecular method for the detection of the mutation was proposed.