Metabolic syndrome is characterised by the concomitance of abdominal obesity, carbohydrates and lipid metabolism, and arterial hypertension. The development of criteria of diagnosing this syndrome in children and adolescents creates great difficulties. The cut-off points in diagnosing an excessive body mass in various age and gender groups still remain the subject for studies and discussions. During the last decade, several definitions of the metabolic syndrome in children and adolescents have been developed. According to the number of studies conducted in various populations with the use of various criteria of diagnosis, metabolic syndrome was observed in 4.2%-9.6% of the population of children and ado-lescents. The occurrence of the syndrome was clearly associated with the degree of overweight and obesity. Such a large prevalence of this syndrome is a great problem for public health, especially that the individual components of the syndrome increase the risk of the development of atherosclerotic plaque in the arteries as early as in the childhood. The prevention of the occurrence of metabolic syndrome at a young age covers adequate nutrition for pregnant women and those who plan pregnancy, adequate control of existing metabolic disorders in future mothers, promotion of breastfeeding, prevention of excessive nutrition since early childhood, promotion of the model of Mediterranean diet, and high physical activity. The implementation of these behaviours on a population scale requires wide educational actions directed towards all population groups, especially to parents, future mothers, children and adolescents. These actions should make use of both the media and any forms of education at school as well as extra-mural education. The co-operation of paediatricians and school nurses is also important.