Undifferentiated embryonal sarcoma of the liver is a rare and aggressive tumor in adults, with an unfavorable prognosis. We present a 33-year-old female patient who was admitted with fatigue, weight loss and right upper abdominal pain. Magnetic resonance imaging of the liver revealed a bulky malignant mass with necrotic and cystic center, which nearly occupied the left lobe and invaded the middle-left hepatic vein and left portal vein. The patient was evaluated as inoperable, and in order to determine the histologic diagnosis, a Tru-cut biopsy was performed. Both histopathologic features and the immunocytochemical stainings revealed the diagnosis of hepatic embryonal sarcoma. Since the patient had no chance of surgery due to the advanced stage of the tumor and progressive hepatic failure, a combination chemotherapy was applied. Unfortunately, the patient did not respond to treatment at all and died in the second post-therapy week. Undifferentiated embryonal sarcoma of the liver is a highly chemo-sensitive tumor. Radical resection may be possible after combination chemotherapy in the childhood period, but since the disease is extremely rare in adults, an optimal treatment approach is still unknown.