A previously healthy 22-year-old woman was admitted with a complaint of right upper quadrant abdominal pain for 2 weeks. Her past history was not remarkable. On admission, HBsAg and anti-HCV were negative and alpha-FP was within normal range. Abdominal sonography and CT showed a mass in liver measuring 10 11 cm with features of central necrosis and hemorrhage. On 6th hospital day, hemoperitoneum developed suddenly. She underwent emergency laparotomy and trisegmentectomy. Intraoperative finding revealed a hemoperitoneum with a tumor filled with liquefied necrotic tissues. Microscopically, the tumor was mostly composed of pleomorphic spindle cells with abundant anastomosing vascular channels and partly composed of tumor cells with trabecular arrangement. On immunohistochemical staining, tumor cells reacted with cytokeratin and vimentin, while CD34 and hepatocyte staining revealed negative. She died 2 months after the operation. We report a case of rapidly deteriorated primary sarcomatoid hepatocellular carcinoma in a young female without any risk factor.