Introduction and objective: In addition to coagulation, vitamin K₂ influences vascular calcification and skeletal mineral balance. Evaluation of its levels and setting reference ranges are mainly relevant for all populations at risk of osteoporosis. However, only few reports have focused on the developmental age population. The aim of this study was to assess vitamin K₂ levels in children with bone fractures. Materials and methods: The study group consisted of 145 children aged 5–17 years, hospitalised for suspected metabolic bone diseases. Patients were divided into three groups: healthy children (n = 68), children with osteogenesis imperfecta (n = 29), and children with traumatic fractures (n = 48). All children were assessed for physical development using established methods, and had their vitamin K₂ levels measured with immunoenzymatic assay (ELISA), using a SunRedBio kit (China). Results: The evaluated group of children showed normal somatic development. Children with osteogenesis imperfecta showed lower height and body weight compared to the other groups. Vitamin K₂ ranged from 0.90 to 12.46 ng/mL in 80% of healthy children. Low vitamin K₂ levels (2.7 ng/mL for osteogenesis imperfecta and 2.05 ng/mL for fractures) were found in groups 2 and 3, and did not differ statistically significantly between children considered healthy and patients with bone fractures, including those with osteogenesis imperfecta. Conclusions: Children with a history of bone fractures have vitamin K₂ levels within the reference ranges for this age group, suggesting that bone fractures in this group are not associated with vitamin K₂ deficiency.