Objectives: Vitamin B12 deficiency is a cause of preventable growth and developmental retardation in children. In this respect, alternative methods such as oral and sublingual treatments are being tried. We aimed to compare the efficacy of oral, sublingual and intramuscular vitamin B12 treatments in children aged 0-3 years. Methods: The study included 158 patients with serum vitamin B12 deficiency (serum vitamin B12 level <300 pg/ml) aged 0-3 years retrospectively. According to the vitamin B12 treatment modalities, the patients were divided into three groups as oral cyanocobalamin (group 1), sublingual methyl-cobalamin (group 2) and intramuscular cyanocobalamin (group 3). Results: The mean values of vitamin B12 levels increased to above 300 pg/ml in all of three groups . This increase was statistically significant for Group 1,2 and 3 (p<0.05). Conclusion: Sublingual methyl-cobalamin was determined as effective as oral and intramuscular cyanocobalamin improving vitamin B12 levels aged 0-3 years.