Hepatocellular carcinoma (HCC) is the third most common cause of cancer death in the world. There has been many advances in diagnosis of HCC during the last ten-year period, especially imaging techniques. The Korean Liver cancer study group (KLCSG), European Association for the Study of the Liver (EASL), American Association for the Study of Liver disease (AASLD) and Asian-Pacific Association for the Study of Liver (APASL) have made and changed HCC guidelines with advances of imaging technique and results of research on HCC. We reviewed the changes of imaging guidelines in HCC diagnosis according to the advances of imaging. In addition, further studies will be needed to solve the controversies in diagnosis of HCC smaller than 1 cm in size.