Aim: The aim of this study was to determine the prevalence of metabolic syndrome in children and adolescents in the county of Primorsko-goranska and Istarska. Also, we analyzed the frequency of certain components and basic antropological and biochemical characteristics of admitted patients. Data from January 2015 to February 2019 was included. Patients and methods: This was a retrospective analysis based on medical documentation of children admitted due to obesity. They were sent by general practitioners. All subjects aged between 6 and 18 years old and with a BMI z-score≥2 were included. Subjects were divided by the BMI z-score into two categories: moderately obese (2-3) and extremely obese (≥3). Results: Total number of subjects was 200. 82 children were classified as moderately obese (41%) and 118 were classified as extremely obese (59%). Total prevalence of metabolic syndrome was 38%, 41% in the extremely obese category and 33% in the moderately obese. The most common component of metabolic syndrome was hypertension, with total prevalence of 61%. The rarest component was impaired fasting glucose, 9,5%. Conclusion: In comparison of our results with the relevant literature, the need for a standardized definition for metabolic syndrome in children was noticed. This is the first study of its kind in the county of Primorsko-goranska and Istarska. Republic of Croatia is lacking such research. Therefore, the results might be useful for comparison with the results in other Croatian regions.