Abstract: Objective To investigate the association of the△3(TTTA)7 short tandem repeat polymorphism in intron 4 of the aromatase(CYP19)gene and the risk of polycystic ovary syndrome(PCOS).Methods Menarche age was recorded.Body mass indices were calculated.Blood samples were obtained for hormone measurements.Total DNA was extracted by Chelex-100 from blood samples.Allele frequencies for the CYP19△3(TTTA)n allele were established from the total DNA using locus-specific prime PCR,followed by electrophoresis of PCR products in denaturing polyacryamide gels and subsequent detection by silver staining.Results Five different alleles containing 7-3(△),7,8,10,11,12 and 13-TTTA-repeats were detected.All allele frequencies were no significative different between the PCOS women and controls.No differences were observed in BMI and serum reproductive hormone levels among individuals with different genotypic features in PCOS.Conclusion Lack of strong association suggested that the polymorphic△(TTTA)n short tandem repeat of CYP19 gene may not relate to the risk of PCOS.