Recurrent miscarriage is often defined as three or more consecutive miscarriages. The incidence of recurrent miscarriage among couples trying to conceive is 1–3%. Recurrent pregnancy loss may be a consequence of an abnormal embryonic karyotype or maternal factors affecting the endometrium resulting in defective implantation. The causes for repeated implantation failure may be because of reduced endometrial receptivity. Various uterine pathologies such as thin endometrium endometriosis hydrosalpinges suboptimal ovarian stimulation altered expression of adhesive molecules and immunological factors may decrease endometrial receptivity. In order to study the endometrial factors responsible for recurrent pregnancy loss endometrial biopsy samples should be precisely timed according to the LH surge and the investigation should be carried out in a non-conception cycle prior to the next pregnancy. The various methods of studying the endometrium including morphological studies morphometry immunohistochemistry measurement of endometrial protein in plasma and uterine flushings cytokine expression in endometrial cells leukocyte populations in the endometrium will be discussed.