The sensitivity of contrast-enhanced harmonic gray scale imaging was compared with that of power Doppler sonography in depicting tumor vascularity and contrast enhancement of hepatocellular carcinoma (HCC) identified by angiography-assisted computed tomography (CT). One hundred thirty-nine classic HCC nodules (108 patients), each appearing as a high-attenuation mass on early-phase CT during hepatic arteriography and as a perfusion defect on CT during arterial portography, were evaluated. Vascular findings and contrast enhancement patterns were evaluated by contrast-enhanced harmonic gray scale imaging. Arterial pulsatile flow into each nodule was checked by power Doppler sonography. Sensitivity of each modality for depicting tumor vascularity was examined by angiography-assisted CT findings as the gold standard. The sensitivity of contrast-enhanced harmonic gray scale imaging (134/139, 96.4%) was significantly greater than that of power Doppler sonography (96/139, 69.1%) (P<0.05). Twenty-six of twenty-seven nodules (96.3%) in the lateral segment, in which motion artifact is likely, were enhanced by contrast-enhanced harmonic gray scale imaging. Contrast-enhanced harmonic gray scale imaging is more sensitive than power Doppler sonography and is a noninvasive method that can be used as effectively as angiography-assisted CT to evaluate tumor vessels and contrast enhancement of HCC.