Endocrine and immune systems are among the most essential regulators of endometrial physiology, and immune-endocrine interactions are likely to be involved in the pathogenesis of endometriosis. Endometriosis is an inflammatory, estrogen-dependent disease defined by the presence of viable endometrial tissue outside the uterine cavity. Impaired immune response that results in inadequate removal of refluxed menstrual debris has been proposed as a possible causative factor in the development of endometriosis. Moreover, decrease in spontaneous apoptosis of endometrium is the other theory proposed for the development of endometriosis. Endometriotic tissues respond to sex steroids aberrantly and behave differently compared to endometrium in addition to their ability to produce local estrogen. The effects of estrogen on distinct intracellular signaling pathways including MAPK, PI3K/AKT and NF-kappaB may take a role in enhanced endometrial cell survival, altered immune response, and differential cytokine and chemokine expression in endometriosis. Better understanding of immune-endocrine interactions will set the stage for effective immune-targeted therapies not only for endometriosis but also for other endometrial diseases such as adenomyosis, recurrent reproductive failure and implantation-related infertility.