Endometriosis is considered a multifactorial disease influenced by genetic predisposition, deficient immune system and environmental factors. The most common symptoms are chronic pelvic pain and infertility. The pathophysiological mechanisms underlying endometriosis and endometriosis-associated infertility are still not well understood. Preliminary studies in our laboratory using gene expression profiling and genetic linkage have resulted in the identification of candidate genes that may play a role in these conditions. The aim of this study was to identify single nucleotide polymorphisms (SNPs) that may be associated to endometriosis and/or infertility in a Puerto Rican population. SNP genotype and allelic frequencies were evaluated in 216 patients and 168 controls, all with surgically confirmed diagnosis. Participants were divided into three groups; GROUP 1- patients with endometriosis vs. no endometriosis, GROUP 2- infertile patients vs. fertile patients and GROUP 3- infertile patients with endometriosis and fertile patients with endometriosis. Allelic frequencies, genotype distribution and multiple regressions were performed. Odd ratios (OR) were adjusted by age. The results show a significant difference between patients with endometriosis and controls with regards to two SNPs (p=0.011, OR=1.3; p=0.026, OR=0.7, respectively). Regarding the infertility status, we found significant differences in two SNPs (p=0.02, OR=2.6 and p=0.005, OR=1.5, respectively). Also, there was a significant difference in another SNP comparing infertile patients with endometriosis vs. fertile patients with endometriosis (p=0.021, OR=1.9). These data suggest that genetic polymorphisms are associated with increased the risk for endometriosis and/or infertility and that a genetic assay could be used to identify patients at risk who could benefit from prevention strategies and close clinical monitoring.(poster)