Objective: To evaluate the impact of gonadotropin-releasing hormone agonist (GnRH-a) used before surgery on natural pregnancy rates in patients with ovarian endometriomas. Methods: In this retrospective study, 57 patients with ovarian endometriomas who had a consecutive laparoscopic surgery between June, 2010 to September, 2015 in Peking Union Medical College Hospital were included. Those patients were divided into preoperative GnRH-a treatment group (n=31) and non-GnRH-a treatment group (n=26) . There were no differences in patients' characteristics between the two groups. All of them had a desire for natural pregnancy postoperatively. GnRH-a was no longer used after surgery. After the surgical procedure, the patients were observed over a period of 12 months, during which the frequency of natural pregnancy was assessed. The two groups were compared in terms of natural pregnancy rates. Results: Totally 33 patients had natural pregnancy after surgery. The univariate analysis showed that the pregnancy rates of age, r-AFS stage, infertility, preoperative use of GnRH-a, tumor size, tumor side, deep infiltrating endometriosis and adenomyosis did not have statistically significant differences (all P>0.05) . The two classified logistic regression showed that OR for preoperative use of GnRH-a was 0.250 (95%CI: 0.064-0.978) with a statistical difference (P=0.046) . Conclusion: The use of GnRH-a preoperatively may have a negative effect on natural pregnancy rates of patients after surgery with ovarian endometriomas.