Primary leiomyosarcomas arising from the ovarian vein are extremely rare and are associated with high morbidity. A 49-year-old nulliparous woman presented with a left lower abdominal mass. Although extremely rare, the radiological appearance is able to preoperatively identify malignant retroperitoneal masses, such as leiomyosarcomas originating from the ovarian vein; thus, the patient underwent a simple total excision of the mass-adjacent organs, as well as complete resection of the uterus, bilateral adnexae and the left ovarian vein. Adjuvant postoperative combination chemotherapy with gemcitabine and docetaxel was administered. At 22 months, she had no recurrence or metastasis. Delayed diagnosis and high metastatic potentiality are associated with the high morbidity of vascular leiomyosarcomas. The preoperative radiological appearance is useful for early diagnosis, and radical treatment with adjuvant chemotherapy consisting of gemcitabine and docetaxel may improve the poor prognosis of patients with leiomyosarcoma arising from the ovarian vein.