Patients with hepatocellular carcinoma (HCC) rarely show marked granulocytosis. We report an interesting case of rapidly growing poorly differentiated HCC associated with marked granulocytosis. The blood leukocyte count decreased following several treatments for HCC, including transcatheter arterial embolization, and increased again along with tumor regrowth. The serum levels of granulocyte colony-stimulating factor (G-CSF) were markedly elevated, and immunohistochemical study showed G-CSF staining in the cytoplasm of certain HCC cells. These findings confirm that HCC in this case was a G-CSF-producing tumor.