Byline: Vera Miodrag Kovacevic, M.D. (a), Luka Momir Andelic, M.D. (a), Ana Mitrovic Jovanovic, M.D., Ph.D. [firstname.lastname@example.org] (b,*) Key Words Endometrioma; laparoscopy; ovarian reserve; antimullerian hormone Objective To investigate the impact of laparoscopic endometrioma cystectomy on the ovarian reserve and to identify the most important factors that predict the ovarian reserve in patients with endometriomas. Design Prospective study. Settings Endoscopy unit of a general hospital. Patient(s) Fifty-four patients with unilateral (n = 37) and bilateral endometriomas (n = 17). Interventions(s) The serum antimullerian hormone (AMH) concentration was assessed before surgery and at 6 and 12 months after surgery. Main Outcome Measure(s) The primary outcome was the damage to the ovarian reserve, as assessed by the serum AMH concentration. Secondary end points were the persistence or recovery of ovarian damage after 1 year. Result(s) AMH concentrations decreased after the laparoscopic excision of cystic ovarian endometriomas. Before surgery and at 6 and 12 months after surgery, the concentrations were, respectively 3.07, 1.29, and 1.46 ng/mL. In the unilateral group, the median AMH levels were 3.31, 1.43, and 1.72 ng/mL, and in the bilateral group the levels were 2.55, 0.98, and 0.89 ng/mL. The serum AMH concentrations thus decreased by 53.27 [plus or minus] 38.2% and 49.43 [plus or minus] 38.3% at 6 and 12 months after cystectomy, respectively. Conclusion(s) In patients with endometriomas, the decrease in ovarian reserve occurs immediately after the excision of the endometrioma. Significant predictors of AMH values at 6 and 12 months after surgery include the baseline AMH level, patient age, and bilateral endometriomas. Author Affiliation: (a) General Hospital, Department of Obstetrics and Gynaecology, Subotica, Serbia (b) "Narodni Front" Clinics for Gynaecology and Obstetrics, Faculty of Medicine, University of Belgrade, Belgrade, Serbia * Reprint requests: Ana Mitrovic Jovanovic, M.D., Ph.D., "Narodni Front" University Clinic for Gynaecology and Obstetrics, Kraljice Natalije 62, 11000 Belgrade, Serbia. Article History: Received 26 December 2017; Revised 18 July 2018; Accepted 19 July 2018 (footnote) V.M.K. has nothing to disclose. L.M.A. has nothing to disclose. G.Z.T. has nothing to disclose. A.M.J. has nothing to disclose.