Introduction: Vitamin D Deficiency (VDD) is defined as the level of 25(OH)D in the serum < 30 ng/ml. According to the contemporary research, even the slight vitamin D deficiency can adversely affect our body in many ways. Numerous studies indicate that vitamin D deficiency is very common in children. The study aimed to research the frequency of vitamin D deficiency in infants and toddlers, the connection between VDD and iron deficiency anemia (IDA), as well as the correlation between 25-hydroxycholecalciferol (25(OH)D) and haemoglobin (Hb) in the examinees. Method: The study includes 150 children, 73 (49%) newborns and 77 (51%) infants. Vitamin D status was determined through the amount of 25(OH)D in blood, using the electrochemiluminescence. Results: Vitamin D Deficiency was found in 58% of infants and toddlers (severe vitamin D deficiency was found in 16% of examinees, vitamin D deficiency was found in 23% of examinees, while vitamin D insufficiency was found in 19% of examinees). Vitamin D deficiency (VDD) and anaemia were found in 80% of examined infants and toddlers. VDD was found in 49% of newborns that were not anaemic. We have observed the substantial difference between the examinees suffering from both anaemia and VDD and the examinees suffering from VDD only. Conclusion: The highest level on anaemia was found in the children with severe vitamin D deficiency, while in the examined infants and toddlers, there was a connection between the level of 25(OH)D and Hb in the serum.