Background:Osteoporosis is a major problem in beta thalassemia major (TM) patients. Increased oxidative stress and its controlling genes were linked to osteoporosis. Glutathione S-transferase P1 (GSTP1),Ile105 Val variant is a functional mutation with reduced ant-oxidative property .No data are available about this variant or its association with osteoporosis among thalassemia patients yet. Objectives: The aim of this study was to investigate Ile105Val polymorphism and its possible association with bone mineral density (BMD) values in a group of TM children. Methods:Thirty five TM patients and 30 age and sex matched healthy controls were included. Liver and renal functions, serum ferritin, calcium, phosphorous, alkaline phosphatase and osteocalcin were assayed. BMD was determined by DXA with calculation of Z-scores at lumbar spine (Ls) and femoral neck (Fn).Height for age z- score (HAZ) adjusted BMD Z-scores were considered . GSTP1 Ile105Val polymorphism was studied by polymerase chain reaction-restriction fragment length polymorphism. Results:The relative frequency of 105 Val allele was significantly higher in TM patients than the controls (P<0.0001). Significant association between genotype subgroups and BMD parameters was detected. Mutant homozygotes had significant lower BMD , Z –score and haz -adjusted BMD Z-score at both Ls and Fn compared to wild homozygotes ( Ps =0.029, 0.008, 0.011, 0.001,0.02, 0.001) with significant higher osteocalcin level compared to heterozygotes and wild homozygotes (P=0.012 and P=0.013,respectively). Conclusion: The results indicated that 105Val allele was frequent among TM patients and could increase their susceptibility to osteoporosis. Large sample studies are required to confirm these findings.