Background. There are an increasing number of children and adolescents with reduced age-related rate of bone mass accumulation, low bone mineral density (BMD) and low-energy fractures. This problem is widely discussed in the scientific literature. Purpose of the study was to assess the BMD in children and adolescents with low-energy fractures of long bones and to investigate some biochemical parameters of bone metabolism. Materials and methods. Body mass index (BMI), bone densitometry, levels of vitamin D, calcium, phosphorus and alkaline phosphatase in blood serum of 230 children and adolescents with low-energy fractures of long bones, aged 6 to 17 years, who underwent treatment due to the fractures were studied. Results. Fractures occurred predominantly in 41.3 % of the humerus and 43 % of the forearm bones. 20 % of children and adolescents had abnormal BMI values. Low BMD values in 86 of 230 examinees were detected in the lumbar spine, of which only 66 (76.7 %) had BMD abnormalities in the hip. In assessing vitamin D status, 19.3 % of the girls and 9.2 % of the boys had normal vitamin D values. A decrease in calcium level and an increase in alkaline phosphatase in blood serum were found. In terms of BMD and vitamin D status, the dependence of boys was statistically significant in the elementary and high school groups, while in girls it was only in the elementary school group. A direct link between low BMD and vitamin D has been established. Conclusions. Low BMD, vitamin D, impaired calcium-phosphorus metabolism and obesity in children and adolescents may be considered predictors of fracture occurrence.