BACKGROUND Apolipoprotein A5 (APOA5) gene variants are associated with increased plasma triglycerides, a risk factor for metabolic syndrome (MS). The goal of the current study was the investigation of the distribution of T-1131C variant among obese adolescents with MS compared with healthy controls. METHODS The study included 150 obese adolescents (75 males and 75 females) with MS and 204 age and sex matched normal healthy controls (100 males and 104 females). The mean age of the patients was 15.47 ± 2.54 years, ranged from 17 to 20 years. They were genotyped by polymerase chain reaction-restriction fragment length polymorphism for the mutation (T-1131C). RESULTS The blood pressure, triglyceride and HOMA-R levels were significantly higher and HDL-C levels were significantly lower in carrier (TC+CC) compared to non-carrier (TT) MS patients. There was accumulation of -1131C allele frequency in the MS group (31.33% vs. control group 11.76%), p<0.001. The genotypes were in Hardy-Weinberg equilibrium both in the patients with metabolic syndrome and in the control subjects. Results of analysis of multiple regression models showed that the ApoA5 -1131C carriers showed an increased incidence of MS (OR=1.73, 95% CI: 1.41-2.11). CONCLUSIONS The present study suggests that the 1131T>C polymorphism is a risk factor for the development of metabolic syndrome in obese adolescents.