We present two patients with hepatocellular carcinoma (HCC) on liver cirrhosis in whom color Doppler sonography documented an incidental peripheral arterioportal fistula due to a previous liver biopsy under laparoscopy. Detection of the fistula helped in preventing the occurrence of a portal thrombus. Color Doppler sonography should be performed prior to transarterial embolization in patients with HCC on liver cirrhosis with a past history of liver biopsy under laparoscopy.