Introduction: Metabolic syndrome includes a range of disorders that increase the risk of cardiovascular disease and diabetes mellitus. In this study, we examined the serum level of vitamin D3 in diabetic individuals with metabolic syndrome compared with non-diabetic individuals without metabolic syndrome and the association of serum vitamin D3 levels with metabolic syndrome and atherogenic factor (LDL/HDL). Material and Methods: In a case-control study, we included 110 women with metabolic syndrome according to ATP III criteria and 127 healthy women as a control group. Serum concentration of total cholesterol, LDL-C, FBS, HDL-C and serum triglyceride determined by enzymatic method and colorimetric and, serum level 25-(OH) vitamin D determined by ELISA. Results: It was found that the two healthy and metabolic groups were significantly different in terms of total cholesterol levels, LDL and triglyceride levels, HDL, VLDL, FBS, atherogenic index (LDL/HDL) and vitamin D levels (p<0.05). All participants in the control group and the patient and the whole study population were divided into two categories of insufficient and sufficient based on their measured serum concentrations of 25-(OH) vitamin D. There was a significant difference between the group with insufficient levels of vitamin D in comparison with the group with sufficient levels of vitamin D in terms of total cholesterol, LDL and triglyceride levels, HDL, VLDL, FBS and atherogenic index (LDL/HDL) (p=0.000). Conclusion: The present results showed that there is a significant relationship between level 25-(OH) D and atherogenic index (LDL/HDL) and the incidence of metabolic syndrome.