The aim of this systematic review was to collect all available randomized controlled trials on the effect of folate supplementation on folate status and health outcomes within the paediatric age group. The method included a structured search strategy on MEDLINE, Embase and Cochrane databases, with formal inclusion/exclusion criteria and data extraction procedure. We included 26 studies. We conclude that both serum and erythrocyte folate values reflect folate intake; however, serum folate reacts more rapidly to folate intake than erythrocyte folate. As to health outcomes, we found no evidence indicating that additional intake of folate can influence haematological parameters in non-anaemic paediatric patients. We were unable to find evidence of a favourable effect of folate supplementation on the growth of infants. However, the limited data available suggest that supplementing the diet of low-birth-weight infants with folic acid may moderate the rapid fall of serum and red cell folate in the first months of life.