Retroperitoneal leiomyosarcoma is a rare neoplasm for which complete surgical removal provides the only effective treatment, as local recurrence adversely affects prognosis. However, invasion of major vessels may occur, making complete resection difficult. This report describes the cases of three patients who required concomitant resection of parts of the inferior vena cava because of direct tumor invasion. The major vessels should be isolated in preference to the tumor capsule during surgery to prevent sudden exsanguination or incomplete tumor resection. Resection of a recurrent sarcoma or a solitary metastasis can be effective in selected patients.