The aim of this study was to quantitatively measure tissue blood flow (TBF) in hepatocellular carcinoma (HCC) by a noninvasive method using xenon (Xe) inhalation/CT scans and to correlate the measured TBF with histological features. TBF was measured in HCC with xenon-enhanced CT (xenon/CT) in 20 patients. In 15 patients with HCC diagnosed as hypervascular tumors by conventional CT, TBF of the tumors was significantly higher than that of noncancerous liver tissue (151.1 +/- 20 vs 42.6 +/- 20 ml/min/100 g). Histologically, these tumors were diagnosed as moderately-to-poorly differentiated HCC. In contrast, in five patients with hypovascular HCC, TBF of HCC was almost comparable to that of the noncancerous regions (45.3 +/- 6 vs 48.3 +/- 6 ml/min/100 g). All these tumors were well-differentiated HCC. In conclusions, the measured values of TBF correlate with the clinicopathologic features of liver tumors and nontumorous liver tissue in patients with HCC.