OBJECTIVE: To present two cases of patients with hyper-reactio luteinalis at the cesarean section. DESIGN: Case report. SETTING: Department of Obstetrics and Gynaecology, Hospital Trenčín; Medirex Group Academy n.o., Bratislava. CASE REPORT: We report two cases of women with preeclampsia who we diagnosed with bilateral multi-cystic ovarian enlargement by chance during cesarean section. At both of them the level of human chorionic gonadotropin was above normal, one of the patients had medical history of ovarian serous borderline tumor and this pregnancy was multiple after in vitro fertilization and embryo transfer. Adnexectomy, resection of ovaries and biopsy were carried out. Histologically hyperreactio luteinalis was confirmed in both patients. CONCLUSION: We discuss the necessity of surgical treat-ment, the authors want to emphasize the need for proper preoperative diagnosis and indication of conservative management of patients with hyperreactio luteinalis.