A 55-year-old woman was found to have mass in the right lobe of the liver by computed tomography and ultrasonography. Hepatic arteriography showed that the mass was hypovascular. Tumor biopsy showed most of the specimen AH but small portion of it was well-differentiated hepatocellular carcinoma. Six moths later, AFP increased and echo pattern of the main mass was changed and furthermore we detected another masses. Hypervascular mass appeared in part of the main mass by appeared in part of the main mass by arteriography, and then TAE and PEIT were performed. After the treatment AFP decreased but six months later AFP increased again. Tumor biopsy of the main mass was diagnosed as Edmondson type I hepatocellular carcinoma, which was more undifferentiated than the earlier specimen. This case suggests that borderline lesion, which is difficult to diagnose as AH or hepatocellular carcinoma, may soon or later progress to obvious hepatocellular carcinoma, and so we must carefully follow up such cases.