An unusual case of a massive liver tumour composed of rhabdomyosarcoma with a small focus of hepatocellular carcinoma in a 52-year-old man is presented. He had hepatitis B virus (HBV) surface antigen in his serum. Macroscopically, a large tumour with satellite nodules occupied the right lobe of the cirrhotic liver. Microscopically, the tumours were composed of small and short spindle-shaped undifferentiated cells, mixed with desmin-positive round rhabdomyoblasts and elongated striated muscle cells, strongly suggestive of rhabdomyosarcoma of the liver. Elevated levels of alpha-fetoprotein in the serum led us to examine the liver tumour closely in multiple sections, which disclosed a hepatocellular carcinoma component measuring 2 cm in diameter within the massive tumour. Immunohistochemically, the hepatocellular carcinoma cells were alpha-fetoprotein positive. There was neither a tumour capsule, nor distinct demarcation, and cytokeratin-positive clusters of undifferentiated cells were intermingled with the hepatocellular carcinoma and rhabdomyosarcoma at the border. The invading tumour outside the liver and metastatic tumours were pure rhabdomyosarcomas. It is suggested that the present case should be diagnosed as rhabdomyosarcoma transformed from hepatocellular carcinoma.