Endometriosis is a common cause of infertility, primarily due to the ectopic implantation of endometrial tissue in the pelvic cavity or other locations. Endometriosis leads to infertility mainly because it affects ovarian function, such as causing ovulatory disorders. Additionally, endometriosis can cause pelvic adhesions, affecting the function of the fallopian tubes, such as their ability to pick up eggs. Women with infertility should be checked for endometriosis, and if confirmed, surgical or medicinal treatments can be considered to improve the condition and potentially increase the chances of conception. Therefore, endometriosis is a cause of infertility, and careful examination for endometriosis should be conducted in patients with infertility.