Background and Aims. We investigated the association between the two common polymorphisms, C1431T and Pro12Ala of PPAR gamma gene, and metabolic syndrome (MS) in a Chinese population. Methods. We included 423 subjects with MS and families without MS. Subjects were divided into three groups: MS probands and first- and second-degree relatives of probands, spouses and controls. Each group was then divided into two subgroups according to genotype (Pro/Pro and Pro/Ala for Pro 12Ala, CC and CT + TT for 1431 C/T). Anthropometric indices, fasting plasma glucose, lipid profile, Sv1 + Rv5 of electrocardiogram and single nucleotide polymorphisms were detected. Results. Frequencies of C 1431 T genotypes, but not Pro12Ala, were different among the three groups. MS patients with Pro/Ala genotype had higher fasting blood sugar (FBS) levels and Sv1 + Rv5. Controls with Ala allele had lower total cholesterol levels. In relatives, Ala carriers had higher high-density lipoprotein cholesterol (HDL-c) levels. BMI of the different groups were not significant. MS patients with T allele had higher FBS and Sv1 + Rv5. In relatives of MS subjects, T-allele carriers had lower blood uric acid, creatinine and higher HDL-c levels and Sv1 + Rv5. Conclusions. C1431T, but not Pro12Ala polymorphisms, are associated with MS in a Chinese population. In MS patients, Ala allele and T allele are both associated with higher fasting blood sugar and higher left ventricular voltage. In controls, Ala carriers have lower total cholesterol. In MS relatives, Ala carriers had higher HDL-c levels and T-allele carriers had lower uric acid, creatinine and higher HDL-c levels and left ventricular voltage. (c) 2009 IMSS. Published by Elsevier Inc.