Metabolic syndrome is a clinical term encompassing risk factors (obesity, insulin resistance, dyslipidemia and hypertension), which yield an increased risk for the development of diabetes mellitus type 2 and cardiovascular disorders in adolescence. Two sets of criteria for diagnosing metabolic syndrome were applied, the criteria for adults, specifically adapted for children, and the criteria defined by the International Diabetes Federation (IDF). A reliability analysis was conducted; sensitivity (SE), specificity (SP), positive predictive value (PPV) and negative predictive value (NPV) of applying certain criteria of both definitions of metabolic syndrome. Metabolic syndrome in adolescents was diagnosed much more frequently using the specific criteria (41%) in comparison to the IDF criteria (22%). Using the specific criteria for children and adolescents, it was established that the HDL cholesterol was the most specific and had the largest PPV. Using the IDF criteria for diagnosing metabolic syndrome, the reliability analysis established that the highest PPV was recorded with the elevated level of triglycerides. The specific criteria have been found to be more efficient in diagnosing metabolic syndrome in adolescents. The highest predictive value was displayed by dyslipidemic disorders, hypertriglyceridemia and hypo HDL cholesterolemia.