Summary: Hypertensive children present with clinical and laboratory phenotype typical of metabolic syndrome (MS) and associated abnormalities such as tendency to hyperuricemia. The typical feature of hypertensive child is disturbed body composition. According to International Diabetes Federation pediatric definition of MS, the prevalence of MS in general pediatric population in age 10–18 years in Poland is in the range 2–3,9%. In contrast, among hypertensive children the prevalence of MS is about 20%. It is documented that MS is the main determinant of hypertension mediated organ damage in hypertensive children.