The patient was a 37-year-old woman who had suffered from repeated pyelonephritis. Computed tomography (CT) of the abdomen revealed a 1.9 cm retroperitoneal mass with compression of the right ureter and hydronephrosis. The patient visited our medical center and admitted. The patient underwent a simple total excision of the mass and end-to-end ureteral anastomosis. The tumor involved right ovarian vein and right ureter. Histopathological diagnosis was leiomyosarcoma of the ovarian vein. At 12 months after operation, local recurrence of surroundings tissue of the right ureter and gallbladder, and inferior vena cava invasion is found. Thus, the patient underwent a right nephroureterectomy with partly resection of the inferior vena cava and en block excision of the gallbladder. While CT revealed no recurrence three months after the operation, adjuvant postoperative combination chemotherapy with gemcitabine and docetaxel was administered. Nine cases of this leiomyosarcoma arising from ovarian vein have been reported in the literature. Leiomyosarcoma arising from ovarian vein with hydronephrosis is a second example.