A case is reported of hepatic arterioportal venous (AP) fistula after a blind needle biopsy of the liver performed ten years ago. AP fistula was discovered incidentally by color Doppler sonography when a 54-year-old man was admitted to our department for further examination of a liver tumor pointed out at another hospital. He had a history of chronic hepatitis diagnosed by histology on a blind liver needle biopsy ten years ago. Sonography demonstrated a hepatocellular carcinoma on liver cirrhosis, but did not reveal any vascular anomaly or cystic lesion in the hepatic parenchyma. Color Doppler sonography visualized not only arterial flow within the tumor but also small color-filled tubular lesion a few centimeters from the tumor. Doppler signals were grossly divided into three types of waveforms: a) pulsatile, b) continuous, and c) severely turbulent. No feeding artery or drainage vein was visualized, and an accurate relationship between this lesion and neighboring vascular systems could not be clarified by color Doppler sonography. Angiography only showed a tumor stain but careful opacification of the hepatic artery later demonstrated an AP fistula 2 cm from the tumor. Needle puncture of the liver is now an indispensable procedure in the diagnosis and treatment of liver disease, and the incidence of iatrogenic fistula seems to be increasing. Untile recentry, intrahepatic vascular fistulae have been diagnosed by angiography or dynamic CT. Color Doppler sonography has now been introduced for use in the abdominal domain, and intrahepatic vascular diseases can be easily and accurately diagnosed using this method. We strongly recommend that color Doppler sonography be performed before angiography, particularly in patients with a history of liver biopsy.