This study assesses the diagnostic value of Lipiodol (iodized oil) and computed tomography (CT) in detecting hepatocellular carcinoma (HCC). Twenty-four patients who were suspected of having HCC received injections of a small amount of Lipiodol, along with an antitumor agent, in the hepatic artery following routine celiac angiography. CT scans obtained 7-10 days after Lipiodol administration demonstrated HCC in distinct contrast to the surrounding noncancerous parenchyma. In particular, the CT-Lipiodol procedure disclosed many small HCC lesions that were not shown by celiac angiography, scintigraphy, CT with and without contrast medium enhancement, and ultrasonography. Although this procedure may miss very small or highly fibrotic lesions, it is recommended for patients suspected of having HCC and for patients for whom hepatic resection is being considered.