Introduction & Objective: Metabolic syndrome is one of the main health problems raised around the world and vitamin D deficiency is a possible new risk factor. The aim of this study was to understand this relationship in the Iranian population.

Materials & Methods: This case-control study was done on 186 subjects over 20 years referred to endocrine clinic in the spring and summer of 2011. Clinical and laboratory data were col-lected using questionnaires . After determining the subjects with metabolic syndrome accord-ing to ATP III criteria and the control group ,blood samples of all participants were taken to measure 25-hydroxyvitamin D levels and sent to the laboratory. The collected data were ana-lyzed with statistical software SPSS v.16.0 and Pearson's chi square test.

Results: Comparing vitamin D levels between the healthy individuals and the patients showed significant differences between the two groups (32.6± 16.5 in the control group vs.17.3± 10.7 in the case group). In the patients, those with vitamin D deficiency compared with those with normal levels of vitamin D, had higher levels of BMI and triglycerides and lower levels of HDL cholesterol.

Conclusion: It seems that vitamin D-deficient individuals have a greater chance of having metabolic syndrome. However, prospective studies are needed to prove this relationship.