Spontaneous regression of hepatocellular carcinoma (HCC) is a rare phenomenon. We followed a detailed clinical course of a spontaneous and complete disappearance of HCC during a short interval. A 73-year-old man with hepatitis B virus infection presented with a 15-mm mass in the right anterior superior segment of the liver. The mass was diagnosed as HCC by imaging findings. We found an elevated serum α-fetoprotein (AFP) level of 748 ng/ml. The tumor regressed to 6 mm on imaging examination, and the AFP serum level decreased to 87.8 ng/ml 1 month after the diagnostic hepatic angiography. Therefore, the patient was followed up without any treatment for HCC. The tumor disappeared 5 months later when the AFP serum level was 5.0 ng/ml. The diagnostic hepatic angiography might have had some effect on the spontaneous regression of HCC in the present case.