chii-Ruey tzeng 1,2* endometriosis shares similarities with several autoimmune diseases. the human leukocyte antigen (HLA)-C genotype is associated with several human autoimmune diseases. HLA-c is a ligand of killer cell immunoglobulin receptors (KIRs) and is an essential regulator of natural killer cell activity, which is associated with endometriosis progression. polymorphisms in HLA-C and KIR affect the activity of NK cells and susceptibility to several diseases. Therefore, we attempted to investigate an association between HLA-C genotype and KIR polymorphism and the occurrence of endometriosis. We tested the association of certain KiR and HLA-c combinations and the development of endometriosis by characterizing both KIR and HLA-C genes in 147 women with endometriosis and 117 controls. The HLA-C genotypes and KIR polymorphisms were analyzed via DnA-based method for higher-resolution genotyping. We found that the occurrence of HLA-C*03:03*01 was increased in endometriosis than in control groups. Analysis of various KIR haplotypes revealed differences between the endometriosis and control cohorts. the number of KIR centromeric A/A haplotypes was increased in the endometriosis group than controls. Moreover, the endometriosis cohort was characterized by reduced number of KIR2DS2-positive individuals in the Han Chinese population. Our current findings suggest that the KIR and HLA-C genotypes are associated with the pathogenesis of endometriosis. Endometriosis is a chronic gynecological disease with unknown etiology and is characterized by extra-uterine growth of endometrial tissue 1. Endometriosis affects 6% to 10% of fertile women at the reproductive age and causes severe pelvic pain and infertility 2-4. Familial and twin studies have reported that genetic factors are associated with the pathogenesis of endometriosis 5-9. Cell-mediated and humoral immune responses are essential in the pathogenesis of endometriosis, since it is associated with various immunological abnormalities, particularly