We assessed a possible correlation between the hepatic tumor index (as the ratio of the tumoral peak systolic velocity to the peak systolic velocity of the right or left hepatic artery) and grade of tumor vessel in large hepatocellular carcinomas (HCCs). Color Doppler sonographic findings were evaluated and compared with selective hepatic arteriographic findings in 78 patients with 93 hepatocellular carcinomas larger than 2.0 cm in diameter. Pulsatile color flow images were obtained in 78 of 93 lesions. The hepatic tumor index was equal to or greater than 1.0 in 57 of 78 lesions. These lesions were revealed arteriographically to have distinct tumor vessels and/or arteriovenous shunting. When this index was 1.0 or greater, we calculated 90% accuracy in distinguishing HCCs with distinct tumor vessels from those without distinct tumor vessels. The hepatic tumor index correlated with the grade of tumor vessels and the presence of arteriovenous shunting.