Clinical case. The article presents a clinical case of malignant retroperitoneal schwannoma, which was a diagnostic finding. The clinical picture of the disease was dominated by pain in the lower abdomen and lower back, frequent urination. After a diagnostic examination and preliminary preparation, the patient was operated on in a hospital at the oncogynecology department of the Tashkent City branch of the Republican Specialized Scientific and practical Medical Center of Oncology and Radiology with a preliminary diagnosis of an ovarian tumor. Interrooperatively, a tumor of the retroperitoneal space with lesions of the obturator nerve was revealed. Subsequently, immunohistochemical analysis clarified the histological type of the tumor, which turned out to be a malignant schwannoma of the retroperitoneal space.Conclusion. These data may help in the management of patients with this pathology and improve the diagnosis of patients with small pelvic tumors.