On combined genotypic analysis of GSTT1 and GSTP1 polymorphisms, a significantly higher frequency of GSTT1null/GSTP1-AG (16%) was observed in cases compared to 3.3% in controls and associated with increased ALL risk (OR = 4.93, 95% CI = 1.76–9.61, p = 0.003). This evidence concerns the gene GSTP1 and acute lymphoblastic leukemia.