Preserving the fertility of patients with multiple primary gynecological malignancies is a pressing issue in reproductive medicine. Organ-preserving treatment, combined with assisted reproductive technology, enables these patients to achieve their reproductive plans. From August 2022 to May 2025, assisted reproductive technology programs were conducted to preserve fertility in a cancer patient with synchronous malignant neoplasm of the endometrium stage TIA1 and ovary stage T1a without signs of stromal invasion in a borderline endometrial tumor. The patient underwent successful primary organ-preserving treatment in 2018 and repeat treatment in 2020 for recurrent endometrial cancer. Given the absence of disease progression over two years, the patient entered a program of assisted reproductive technology to preserve fertility. From August 2022 to May 2025, she underwent 14 transvaginal follicle punctures in a natural cycle, followed by vitrification of 13 stage MII oocytes using a levonorgestrel-releasing intrauterine system. In 3 cases, oocytes were retrieved from the right ovary, in 10 cases from the left ovary, and in 1 case, no oocyte was retrieved from the left ovary. The patient was observed and examined every 3 months, while using a levonorgestrel-releasing intrauterine system. No signs of recurrence of ovarian cancer or endometrial cancer were detected. © Eco-Vector, 2025. All rights reserved.