One of the important factors affecting bone health is body weight. Underweight children are predisposed to disturbances in bone metabolism, which may result in osteopenia and osteoporosis in later life. OBJECTIVE The aim of the study was to assess the relationship between adipokines, bone metabolism, and anthropometric parameters in underweight prepubertal children. METHODS The study included 60 children aged 5-10 years. Among them, there were: 30 underweight children (BMI z-score ≤-1) and 30 normal-weight children (BMI z-score <-1 + 1 >). Body composition (fat mass, lean body mass, bone mass) and bone mineral density examination were performed by densitometry. Serum concentrations of bone metabolism markers and adipokines were determined by immunoenzymatic methods. RESULTS In underweight children we observed significantly lower fat mass (p<0.0001), lean mass (p<0.001), bone mineral content (p<0.01) and bone mineral density both the total body (p<0.01) as well as lumbar spine L2-L4 (p<0.05) compared with normal-weight children. In the group of underweight children, serum concentration of bone resorption marker (CTX) was significantly higher than in normal-weight children (2.006±0.649 vs. 1.624±0.492 ng/ml, p<0.05), with no differences in the concentrations of osteocalcin and sclerostin between studied groups. The ratio of adipokines (leptin/adiponectin) was approximately 2-fold lower in underweight than in normal-weight subjects. In underweight children we observed positive correlations between concentrations of sclerostin and bone turnover markers (OC, CTX) and between adiponectin and CTX. However, there was no correlation between fat mass and leptin concentration in this group of children. CONCLUSIONS Low body weight in prepubertal period is related with an alteration in the adipokines profile and bone metabolism markers, resulting in a decrease in bone mineral density.