Background:  Polycystic ovary syndrome (PCOS) is one of the commonest endocrine disorder affecting the women in childbearing period. Accumulating evidences from recent studies indicate that vitamin D receptor (VDR)Taq1(Tt) genetic variants may contribute to the pathogenesis of  insulin resistance and polycystic ovary syndrome. The Vitamin-D receptor (VDR) regulates vitamin D levels and calcium metabolism in the body and these are known to be associated with insulin resistance and type-2 diabetes in polycystic ovarian syndrome (PCOS). This study aims to investigate the association of VDR polymorphism Taq1(Tt)and serum 25(OH)D level with PCOS. This study was carried out on140 subjects divided into 2 groups: 70 patients with PCOS (group I) and 70 healthy subjects served as controls (group II). All studied subjects were submitted to full history taking, general clinical examination and laboratory investigations for serum levels of fasting blood glucose, total cholesterol (TC),triglycerides (TG), HDL-c,LDL-c, fasting insulin and 25(OH)D. Also genotyping of VDR polymorphism ( Taq1) was analyzed using the polymerase chain reaction–restriction fragment length polymorphism technique (PCR-RFLP). Results showed high significant statistical differences between the two studied groups regarding BMI (P value <0.001),SBP (P value <0.001) ,DBP (P value <0.001), fasting insulin (P value <0.001), fasting blood glucose (P value <0.001) ,insulin resistance (P value <0.001) ,triacylglycerol (P value <0.001), LDL cholesterol (P value <0.001),  serum level of 25 (OH) Vit D (P value <0.001) and VIT D R Taq1 genotype distribution (p value<0.001) with increased frequency of the tt andTt genotype in patients with PCOS and increased frequency of TT genotype in controls.  Conclusion: Our results indicate that tt genotype and t allele of VDR TaqI polymorphism and serum level of 25OHD might be risk factors for PCOS.