The glutathione S-transferases (GSTs) are a family of enzymes involved in the detoxification of a wide range of chemicals, including important environmental carcinogens, as well as chemotherapeutic agents. In the present study 294 acute leukemia cases, comprising 152 of acute lymphocytic leukemia (ALL) and 142 of acute myeloid leukemia, and 251 control samples were analyzed for GSTM1 and GSTT1 polymorphisms through multiplex PCR methods. Significantly increased frequencies of GSTM1 null genotype (M0), GSTT1 null genotype (T0) and GST double null genotype (T0M0) were observed in the both ALL and AML cases as compared to controls. When data were analyzed with respect to clinical variables, increased mean levels of WBC, Blast %, LDH and significant reduction in DFS were observed in both ALL and AML cases with T0 genotype. In conclusion, absence of both GST M & GST T might confer increased risk of developing ALL or AML. The absence of GST enzyme might lead to oxidative stress and subsequent DNA damage resulting in genomic instability, a hallmark of acute leukemia. The GST enzyme deficiency might also exert impact on clinical prognosis leading to poorer DFS. Hence GST genotyping can be made mandatory in management of acute leukemia so that more aggressive therapy such as allogenic stem cell transplantation may be planned in the case of patients with a null genotype.