We report three new cases of leiomyosarcoma of the inferior vena cava observed between 1985 and 1990. Two of them developed in women and one in a man. The age of the patients were 56, 29 and 57 years. The three tumors have been removed completely. One patient received postoperative radio- and chemotherapy and is well 68 months after excision. One patient developed liver metastasis 18 months after resection despite chemotherapy and died after 3 years. The last one refused postoperative radio- and chemotherapy, developed massive local recurrence and pulmonary metastasis three months postoperatively, and is still alive with disease after 8 months. The diagnostic modalities of these rare tumors as well as the problems created by their surgical resection and the need for a complementary treatment are discussed.