Glutathione S-transferases (GSTs) are enzymes that involved in bio- transformation by conjugation ofelectrophillic compounds to glutathione. Polymorphisms within genes that encode GSTs may affect the functionof the enzymes. Polymorphisms of GSTP1 at codon 105 residue forms GSTP1 active site for binding of hydrophobicelectrophiles, and the Ile-Val substitution affect substrate specific catalytic activity of this enzyme andmay 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 theGSTP1 gene of childhood ALL patients were studied. In addition, the association of genetic polymorphism ofGSTP1 and genetic susceptibility of acute lymphoblastic leukemia (ALL) was also determined using Chi-squareand Odds ratio. PCR-RFLP was used to study genetic polymorphism of GSTP1 in 100 ALL patients and 100healthy individuals.The results show that there is no statistically significant association between each genotypesand genetic susceptibility of acute lymphoblastic leukemia (ALL) (OR=0.92, P –value=0.886). Moreover, thereis no statistically significant association between each genotypes and demographic data of acute lymphoblasticleukemia (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.