BACKGROUND: Folic acid is one of the important supplements for adequate development during pregnancy. A higher intake of folic acid during pregnancy and lactation is recommended. METHODS: In prospective study the group of premature newborns (n = 52) and the type of nutrition were observed. The red blood cell (RBC) folate concentration levels were determined in the fi rst 24 hours after delivery, before and after oral treatment with folic acid (100 μg/day). Immunochemical analysis for the determination of folate in erythrocytes was performed. RESULTS: In the group of premature newborns the RBC folate concentration levels after treatment were significantly increased (p < 0.0001). A dynamic increase in the concentration levels of folates in erythrocytes before and after treatment was observed, in spite of the reciprocally decreasing blood count parameters, but without any statistically signifi cant correlation. The infant nutrition before treatment contained signifi cantly higher amount of folic acid in fortifi ed breast milk compared to breast milk (p = 0.04). CONCLUSION: The various types of nutrition for preterm newborns contain a different amount of folic acid. It poses a question of real needs of these patients. The best way to determine the optimal whole amount of folate is to know the real levels of folate in premature newborns (Tab. 2, Fig. 5, Ref. 26). Text in PDF www.elis.sk. KEY WORDS: folic acid, breast milk, milk fortifi er, preterm formula milks, neonatal nutrition.