OBJECTIVE: Patients with metabolic syndrome are at increased risk of developing cardiovascular disease. The combinations of the haplotype created by the alleles of three single nucleotide polymorphisms (SNPs): SNP-43, SNP-19, and SNP-63 of the Calpain 10 gene (CAPN10), have been reported to be associated with the risk of type 2 diabetes (T2DM) in many populations. The aim of this study was to examine the association of the CAPN10 polymorphisms with metabolic syndrome in Korean patients with T2DM. METHODS: Overall, 382 T2DM patients were enrolled in this study. All the subjects were genotyped according to CAPN10 SNP-43, SNP-19 and SNP-63. The restriction fragment length polymorphism method was used for the three SNPs. The baseline presence of the components of metabolic syndrome was determined. RESULTS: 265 (69.4 %) patients were found to have metabolic syndrome. Patients with the 111/121 haplotype combination showed a higher risk of hypertension than the other haplotype combinations (OR=2.334, P=0.010) and also had a significantly higher risk of having metabolic syndrome (OR=1.927, P=0.042). CONCLUSION: The results of this study suggest a role of the novel 111/121 haplotype combination created by the CAPN10 SNPs -43, -19 and -63 in the susceptibility to metabolic syndrome of T2DM patients.