Background: the aim of this study is to evaluate the prevalence of hyperhomocysteinemia in children with end stage renal disease on regular hemodialysis, the role of vitamin B12 and folic acid in treatment and to study MTHFR (C677T) gene mutation. Methods: the study included forty seven patients with ESRD and on regular hemodialysis (25 males and 22 females) the mean age was 10.08 +/-3.1. Study included also twenty- age matched- healthy individuals as a control group. Homocysteine level in plasma was measured in both patients and control group. Then, the patients with hyperhomocysteinemia are subjected to treatment with vitamin B12 and folic acid in the form of intramuscular injection weekly for four weeks then level of homocysteine was measured again. MTHFR gene mutation was studied in the group with hyperhomocysteinemia. Results: Hyperhomocysteinemia was found in 36% of the patients and this group was subjected to treatment with vitamin B12 and folic acid and then homocysteine level measured again and showed reduction in the mean level near the level of control group. MTHFR gene mutation was studied in the hyperhomocysteinemia group and showed that 11 % homozygous and 29 % heterozygous and normal in 60%. Conclusion: hyperhomocysteinemia is prevalent in patients with ESRD on regular hemodialysis and vitamin B12 in addition to folic acid is important in reduction of homocysteine level.