['Despite being one of common preventable deficiency disorders, vitamin B12 (vit-B12) deficiency can lead to serious health problems both in children and adult. The familiar treatment through parenteral route for vit-B12 deficiency frequently leads to poor adherence, and adequate response to treatment has lead to interest in oral supplementation. This study investigates the efficacy of oral vit-B12 treatment in children with nutritional vit-B12 deficiency.', 'Forty-seven children (from 1 month to 17 years) with vit-B12 levels below 200 pg/mL were allocated either of two study groups: Group 1 (1-20 months) and Group 2 (6-17 years) which were subdivided according to the duration of treatment (Group 1A&2A: 4 months; Group 1B&2B: 8 months of 1000 μg oral vit-B12, every day for a week, every other day for 2 weeks, 2 days a week for 2 weeks, then once a week).', 'Vit-B12 levels among all groups were significantly restored following high oral vit-B12 doses (P = 0.013, P = 0.001), the regimen being more effective in Group1A and Group1B. Correlation analysis of serum vit-B12 levels and age at the end of treatment revealed a decreasing trend with the increasing patient age (corelation respectively -65.2%, P = 0.08; -35.4%; P = 0.25).'] Is oral vitamin B12 treatment effective for children with nutritional vitamin B12 deficiency?