We report on a 43-year-old man with a primary sarcoma of the liver. The patient was admitted to the hospital for evaluation of dyspnea, abdominal pain in the right upper quadrant, diarrhea, and fever. Physical examination revealed hepatomegaly. Increased laboratory values were found for gamma-GT, LDH, CA 125, and NSE, but not for aspartate and alanine aminotransferase. Computed tomography presented a tumor in the right lobe of the liver. Venous cavography revealed a caval tumor thrombus reaching up to the right atrium. Major liver resection combined with replacement of the vena cava inferior was proposed, but before operation the patient complained about shortness of breath. Spontaneous fragmentation of the tumor thrombus with consecutive embolization of the lungs was suspected. Despite lysis therapy the patient died because of right ventricular failure. Autopsy revealed a tumor measuring 8 cm in diameter, which was located in the right lobe of the liver and invaded the inferior vena cava. Because of multiple tumor aggregates seen in the left and right main pulmonary arteries acute tumor embolization of the lungs was regarded as cause of death. Histologically the tumor was composed of bizarre giant cells surrounded by irregular spindle cells. The positive immunoreactivity pattern of the tumor cells for vimentin, lysozym, and CD68 justified the diagnosis of a malignant fibrous histocytoma (MFH) of the liver.