Abstract-Because primary hypertension (PH) is associated with calcium metabolism, it is hypothesized that PH may be related to osteoporosis risk. The study aimed to evaluate the relationship between body composition and bone strength in hypertensive adolescents. Total body scans using x-ray absorptiometry (DPX-L, GE Healthcare) were performed in 94 PH children aged 6 to 18 years (21 girls and 73 boys). References of healthy control subjects were used for the calculation of Z scores (age and gender matched), SD scores (height and gender matched), and SDs scores (weight and gender matched). Total body bone mineral density, total body bone mineral content (TBBMC), lean body mass (LBM), and fat mass (FM) were investigated. Relative bone strength index was calculated as the TBBMC:LBM ratio. As evidenced by Z scores, PH case subjects had slightly higher total body bone mineral density, TBBMC, and LBM compared with healthy subjects. Reduced LBM/body weight (BW) Z scores of Ϫ1.9Ϯ1.5 and Ϫ1.2Ϯ1.4, increased FM Z scores of ϩ2.5Ϯ2.5 and ϩ1.7Ϯ2.0, and increased FM/BW Z scores of ϩ1.6Ϯ1.3 and ϩ1.1Ϯ1.4 were noted in girls and boys compared with healthy subjects, respectively (PϽ0.001). On the other hand, PH is strictly related to sedentary behavior and nutritional habits with high-sodium and low-calcium intake, and both PH and decreased bone mass are among the main problems of elderly persons. 2,5 Calcium, vitamin D metabolites, proper nutrition, and physical activity (PA) are crucial determinants of peak bone mass. 6 -13 It was shown recently that low serum vitamin D levels correlate with higher blood pressure. 14 Therefore, PH, through its possible associations with calcium and vitamin D metabolism, as well as behavioral factors including nutritional habits and low PA, may alter skeletal status and body composition. Bone mass accrual is highly influenced by mechanical stimulation from skeletal muscles, and the proper muscle-bone interactions during growth are key determinants of skeletal adaptation toward changing loads. [11][12][13]15,16 Low PA, excessive sodium intake, and calcium loss are among the risk factors common not only for osteoporosis but also for PH. 16,17 Because exposure to similar risk factors for both osteoporosis and PH takes place already in childhood, it seems interesting to evaluate the musculoskeletal system at an early stage of PH.The method of choice for the evaluation of both skeletal status and body composition is dual-energy x-ray absorptiometry (DXA). 6 -10,18 -22 DXA offers accurate and precise measurements of total body bone mineral density (TBBMD), total body bone mineral content (TBBMC), lean body mass (LBM; predominantly muscle mass), fat mass (FM), and its fraction of whole body mass. 18 -22 Recently, DXA-derived TBBMC and LBM were implemented as the parameters