This article presents a clinical case of a 64-year-old female patient who had not seen a physician for 8 years. The main complaints on admission were dyspnea at rest, sensation of shortness of breath, weakness, forced semi-sitting position. A comprehensive clinical and laboratory examination was performed, which resulted in the diagnosis of a giant ovarian tumor without signs of malignant process. To prevent hypotensive syndrome, as well as to verify the diagnosis (cytology), drainage of the neoplasm was performed under ultrasound guidance with the installation of multi-perforated drainage. During 3 days of follow-up, 33 liters of serous and hemorrhagic discharge of muddy color were passively leaked through the drainage. Cytology report: reactive inflammation. Total hysterectomy with bilateral salpingo-oophorectomy, large omental resection, and peritoneal biopsy were performed. A tumor of 50 × 40 × 42 cm was removed. Body mass index before surgery was 34.5 kg/m2; after surgery – 21.3 kg/m2. Pathology report: mucinous adenocarcinoma without penetration of the ovarian capsule. pT1a, V1, Lv0, Pn0. Conclusion. Tumors with a mean diameter >40 cm should be classified as extremely giant ovarian tumors. Patients with such tumors require a multidisciplinary approach. © 2024, Dynasty Publishing House. All rights reserved.