Undifferentiated (embryonal) sarcoma of the liver (USL) is a rare primary hepatic malignancy principally affecting patients of pediatric age. It is believed to be a primitive mesenchymal neoplasm, which usually behaves in a highly malignant fashion. The median survival has been less than a year. The only chance for cure appears to be radical excision of the tumor. However, some patients may develop recurrent disease despite complete surgical resection of the tumor. Recently, long-term disease-free survival has been achieved in cases which underwent aggressive multimodal treatment. Herein we report on a 12-year-old girl who underwent surgical excision of USL. Histologically, it was composed of pleomorphic stellate or spindle-shaped cells in a myxoid stroma. Characteristic periodic acid Schiff-positive, diastase-resistant intracytoplasmic hyaline globules were seen. Immunohistochemically, the tumor cells were positive for vimentin, alpha1-antitrypsin, and alpha1-antichymotrypsin. In addition, p53 protein was expressed in 40% of tumor cells, and Ki-67 was demonstrated in 45% of tumor cells. Postoperative chemotherapy was recommended, but was refused by the patient's family. A recurrent liver mass was found 171 days after the operation. Chemotherapy was refused once again by the patient's family, and she was lost to follow-up for 5 months. The patient was brought to the outpatient clinic again because of abdominal fullness and back pain. The recurrent tumor was 20 cm in size with compression of the inferior vena cava. She was admitted and received chemotherapy with vincristine, ifosfamide, and cisplatin.