Abstract: Objective To investigate the polymorphisms of the Type 5 17-hydrox ysteroid.dehy drogenase(17β-HSD5)genes in Chinese women with polycystic ovary syndrome(PCOS).Methods Menarche age was recorded.Body mass indices(BMI)were calculated.Blood samples were obtained for single nucleotide polymorphism analyses and hormone measurements.Genotyping of the SNP-71G of the 17β-HSD5 gene by the polymer ase chain reaction-restriction fragment length poly morphism method.Results In general different from Caucasian's 17β-HSD5-71(A/A:G/A:GIG=39:47.5:13.6),the allele G of Chinese women rare.The genotypic distributions of 17β-HSD5(A/A,G/A,G/G)in women with PCOS(0.992,0.008,0,respectively)did not differ from those in controls(1,0,0,respectively).BMI,total T and other reproductive hormones such as FSH,LH,LH/FSH,P and E2 were also similar between the different genotypes of 17β-HSD5 gene in the PCOS subjects.Conclusion There is no association of 17β-HSD5-71G(wild type A)with the occurrence of PCOS in Chinese population.