Abstract: It has been proposed that there is an association between endometriosis and infertility.This review represents a summary of several mechanisms to explain infertility causing by endometriosis.They are including: 1) distorted pelvic anatomy and blocked fallopian tube.2) altered peritoneal environment peritoneal fluid alterations including cell-mediated immunity(macrophages,T lymphocytes),humoralmediated immunity and hormonal(prolactin,estrogens and progesterone) concentration.3) altered endometrial receptivity and embryo implantation and 4) psychological factors.