Leiomyosarcomas of vascular origin is a rare and aggressive pathology, its presentation on the renal vein is infrequent, of which 29 cases have been reported world-wide. We describe a case of a 76 year-old woman, who presented with intermittent left flank pain, irradiated to the lumbar region of 6 months duration. A left radical nephrectomy with en-bloc resection of a para-aortic tumor was performed. Microscopic examination of the specimen reported a moderately differentiated leiomyosarcoma, originated in the wall of the renal vein. The patient received adjuvant chemotherapy and radiation therapy. The tumor recurred in the liver. After 24 months from the primary surgery, the patient is alive with evidence of multiple metastatic spread to the liver. She is now under palliative care.