In the current study, we aimed to scrutinize the expression levels of miR135a in eutopic and ectopic tissues in the patients with endometriosis compared to control samples throughout the menstrual cycle and its role in the regulation of HOXA10. The results showed a remarkable increase in the miR-135a expression in the luteal phase in the case-eutopic endometrial tissue as well as a significant decrease in the case-ectopic endometrial tissue. The gene discussed is HOXA10; the disease is endometriosis.