Background: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common enzyme disorder in human. The aim of this study was to determine the prevalence of G6PD deficiency among children and evaluate its association with ABO/Rh blood groups. Method: Blood samples of 3401 asymptomatic children were analyzed and compared with 317 children who were admitted to hospital because of hemolysis resulted from G6PD deficiency. Results: Among asymptomatic children 375 (11%) were G6PD deficient. Male to female ratio for this group was 4.2:1 and for the hemolytic group was 2.5:1 (P=0.004). Two hundred and sixty-seven (84.2%) of the patients with hemolysis were younger than 2 years, with the peak age of hemolysis between 2 and 3 years (27.7%). The overall rate of hemolysis caused by G6PD deficiency was 12.3% during the 3 consecutive months of fresh Fava bean consumption. Blood groups O+, A+, and B+ together constituted 87.1%, 87.7%, and 84% of the blood groups among normal children, asymptomatic G6PD deficient subjects, and those with G6PD deficiency related hemolysis respectively (P=0.367). Seven percent of the normal children and asymptomatic G6PD deficient subjects were Rh- vs 9.7 % of G6PD deficient children with hemolysis (P=0.16). Conclusion: The prevalence of G6PD deficiency among the children was 11%. Male to female ratio was greater in non- hemolytic vs hemolytic group so that the female share was higher in hemolytic group than in the other two groups (P=0.004).The distribution of ABO blood groups was similar among asymptomatic non-G6PD deficient, asymptomatic G6PD-deficient, and G6PD-deficient children with hemolysis. The distribution of Rh- types among the G6PD-deficient children with hemolysis and the other two groups was similar (9.7% vs 7%, P=0.16).