Vitamin B12 deficiency is traditionally treated with intramuscular injections of cobalamin, which are stressful events for children. In adults, studies have shown adequate absorption of intranasally administered vitamin B12. To date, data concerning efficacy of intranasal administration of vitamin B12 in children are lacking. We report on ten cases of children with vitamin B12 deficiency who were successfully treated with intranasal administration of a spray containing hydroxocobalamin. The mean baseline vitamin B12 concentration increased from 126.3 pmol/l (SD 55.4) to 1914.7 pmol/l (SD 1509.7). No side effects were reported. Conclusion: In children, intranasal application of vitamin B12 seems a safe and effective alternative to intramuscular injections, leading to higher compliance and less burden to patients.What is Known:• Children with vitamin B12deficiency are traditionally treated with intramuscular cobalamin injections, which are costly and painful.• Studies in adults showed that intranasal application of hydroxocobalamin leads to normalisation of vitamin B12levels.What is New:• The intranasal application of vitamin B12resulted in a substantial increase of the mean baseline vitamin B12levels without any side effect.• These data encourage a systematic evaluation of intranasal treatment of vitamin B12deficiency in order to define safety, optimal dosage and administration frequency.