© 2017, Indian Society of Haematology & Transfusion Medicine.The purpose of this study was to evaluate the relationship between the plasma holoTC and serum vitamin B12 in children and to identify a cutoff cobalamin values according to holoTC. One hundred and fifty-five children were enrolled into the study. All children were evaluated for hemoglobin, vitamin B12, folate, ferritin and holoTC levels. Children were grouped as with low vitamin B12 level (≤200 pg/mL, group I) and normal vitamin B12 (>200 pg/mL, group II). Serum vitamin B12, and holoTC levels were performed in each patient in the study. In 101 patients with low vitamin B12 (group I) the mean holoTC was 21.74 ± 1.14 pmol/L. In 54 children with normal vitamin B12 (group II) mean holoTC was 44.0 ± 2.7 pmol/L (p < 0.01). A ROC curve analysis was performed to delineate the optimum cut-off point for vitamin B12 level and it was found to be 165 pg/mL with a sensitivity of 70% and specificity of 74%; the area under curve was 0.783 (p < 0.01). Our study displayed a positive correlation between vitamin B12 and holoTC, and defined an optimum cutoff value for vitamin B12 as 165 pg/mL. Further studies using the markers both MMA, tHcy and holoTC to confirm the findings are needed.