Glutathione S-transferases (GSTs) are enzymes that involved in bio- transformation by conjugation of electrophillic compounds to glutathione. Polymorphisms within genes that encode GSTs may affect the function of the enzymes. Polymorphisms of GSTP1 at codon 105 residue forms GSTP1 active site for binding of hydrophobic electrophiles, and the Ile-Val substitution affect substrate specific catalytic activity of this enzyme and may associate with susceptibility to malignant human disease, especially acute lymphoblastic leukemia (ALL), which is the most common leukemia in children younger than 15 years old. Genetic polymorphisms within the GSTP1 gene of childhood ALL patients were studied. In addition, the association of genetic polymorphism of GSTP1 and genetic susceptibility of acute lymphoblastic leukemia (ALL) was also determined using Chi-square and Odds ratio. PCR-RFLP was used to study genetic polymorphism of GSTP1 in 100 ALL patients and 100 healthy individuals.The results show that there is no statistically significant association between each genotypes and genetic susceptibility of acute lymphoblastic leukemia (ALL) (OR=0.92, P -value=0.886). Moreover, there is no statistically significant association between each genotypes and demographic data of acute lymphoblastic leukemia (ALL). However, there are 2 cases of ALL with BM relapse show the polymorphic genotypes of GSTP1. It may suggest that GSTP1*V105 may be involved in relapse of ALL.