N-acetyltransferase2 (NAT2) and Cytochrome P4502E1 (CYP2E1) are two drug metabolizing enzymes. Antituberculosis drug isoniazid is acetylated by NAT2 and forms ultimately a nontoxic compound which is metabolized by CYP2E1 to a toxic metabolite. Slow acetylator genotype of NAT2 and wild type genotype of CYP2E1 gene has been attributed to greater toxicity of ATT drug. Therefore this study has been designed to analyze the genetic polymorphism of NAT2 and CYP2E1 genes in tuberculosis patients who developed drug induced hepatitis upon administration of antituberculosis drug.Polymorphism study of NAT2 and CYP2E1 gene may help in predicting the high risk group of ATT induced hepatitis.