Primary hepatic leiomyosarcoma is very rare and no primary myxoid leiomyosarcoma in the liver has been reported yet. Most cystic space-occupying lesions in the liver are benign in nature. But, rarely, malignancy could appear as a cystic lesion by ultrasonographic examination. A 64-year-old woman with a huge cystic mass detected by hepatic ultrasonography was diagnosed as primary hepatic myxoid leiomyosarcoma by immunohistochemical and ultrastructural studies after various image studies and fine needle aspiration biopsy of the liver mass.