Advanced hepatocellular carcinoma (HCC) with tumor thrombus extending through the hepatic veins, inferior vena cava, and right atrium (RA) is very rare. However, whether active treatments such as radiation, transcatheter arterial chemoembolization, and sorafenib in advanced HCC with RA involvement prolong survival is uncertain. We present a rare case of advanced HCC with tumor thrombus nearly occupying the entire RA that was treated with sorafenib. The patient received 400 mg sorafenib twice daily. However, her liver enzyme levels continued to increase and abdominal computed tomography showed an increase in the tumor size in the liver and RA. In the present case, active treatment with sorafenib was ineffective; thus, palliative care may be more beneficial in advanced HCC with extensive RA involvement. (J Liver Cancer 2018;18:142-145)