Sixty-six cases of leiomyosarcoma of the inferior vena cava (IVC) have been reported. We present another case and review the characteristics and treatment of this rare tumor. IVC leiomyosarcomas spread by extension into adjacent tissue planes. Direct extension into the heart is known, but not into the kidneys, adrenals, or bowel. IVC leiomyosarcomas arising below the renal vein cause pain in the right-lower quadrant, back, and flank, and varying degrees of lower extremity edema; those arising in the middle caval segment cause right-upper-quadrant pain and sometimes renovascular hypertension; those arising above the hepatic vein cause varying manifestations of the Budd-Chiari syndrome. A reasonable approach to early diagnosis involves oral and intravenous contrast studies followed by computed tomography, angiography, and vena cavography. Aggressive surgical treatment is optimal in light of the tumor's slow growth pattern and relatively low malignant potential. (Metastases have been reported in fewer than 50% of cases). Tumors involving the lower IVC are most amenable to surgery; extensive collateral venous drainage of the left kidney preserves renal function during resection of middle caval tumors. Upper caval leiomyosarcomas are the least amenable to complete removal. Postoperative survival of all patients has ranged from a few weeks to eight years.