The aim of our investigation was to determine the impact of the degree of obesity on metabolic characteristics in children and adolescents with metabolic syndrome. We studied 117 children and adolescents 8-15 years of age with BMI exceeded the 85th percentile for their age and sex and the complaints associated with obesity. Investigated patients were divided according BMI percentiles for age and sex established by the U.S. Centers for Disease Control and Prevention (CDC) as follows: Group 1. Overweight (OW; 85-94.99th percentiles, n=10); Group 2. Obesity of I degree (Ob1; 95-96.99th percentile, n=12); Group 3. Obesity of II degree (Ob2; 97-98.99th percentile, n=51); Group 4. Obesity of III degree (Ob3; >98.99th percentile, n=39). Plasma glucose levels (fasting plasma glucose - FPG, postprandial plasma glucose - PPG) were determined by glucose oxidase method and Serum lipid (total cholesterol, HDL-cholesterol, LDL-cholesterol, VLDL-cholesterol, Triglycerides) levels have been measured. Plasma C-peptide, fasting plasma insulin (FPI), postprandial plasma insulin (PPI) and Leptin levels were determined by Enzyme-linked Immuno-Sorbent Assay kits. Like adults, the children and adolescents in our study were classified as having the MS if they met three or more of the following criteria for age and sex: 1) a WC≥90th percentile or 1a) WC/Height≥0.05, 2) a triglyceride level above the 95th percentile, an HDL cholesterol level below the 5th percentile,3) systolic or diastolic blood pressure above the 95th percentile, and 4) impaired glucose tolerance or insulin resistance. Metabolic syndrome was diagnosed in 68 cases (out of 117; 58.12%). The results of FPG, PPG, FPI, PPI, serum C-peptide and HOMA-IR in groups shows that FPG and PPG have not significant difference in between groups (p=NS). FPI, PPI, C-peptide and HOMA-IR-were significantly increased by the increase of degree of obesity. The values of systolic BP are significantly higher in Ob2 and Ob3 rather that OV and Ob1 groups. It has not been detected significant difference between diastolic BP values. The levels of total cholesterol, VLDL-cholesterol, and Triglycerides are significantly lower in group 1 (OV) than analogous values of other obese groups. HDL-cholesterol was significantly sharply lower only in group 4. Triglyceride and leptin levels are sharply significantly higher in Ob3 group in comparison to others. The degree of obesity in children and adolescents has important clinical implications. Data on the prevalence of severe obesity in children and adolescents do not exist, to our knowledge. Our results show a significant adverse effect of worsening obesity on insulin resistance, glycemia, lipids and blood pressure, underscoring the deleterious effect of increasing BMI percentile.