Purpose: To evaluate the hemodynamics of nodular hepatocellular carcinoma (HCC) using single-level dy-namic CT during hepatic arteriography (CTHA) according to the size of the nodule.Materials and Methods: Forty 40 patients with nodular HCC confirmed histologically or radiologically under-went single-level dynamic CTHA. Contrast media was injected via the hepatic artery for 20 seconds at a rate of 1.2 ml/sec. Images were obtained prior to this and thereafter at 3-second intervals until 30 seconds after the start of injection, and additional images at 45 and 60 seconds. The CTHA findings were retrospectively re-viewed,and cases were assigned to one of three groups, according to the size of the tumor [ 5 cm (group III, n =16)]. We focused on onset time of contrast en-hancement (CE), peak CE time and density, and duration of plateau. The patterns of CE were classified as ho-mogeneous,heterogeneous, peripheral, or “nodule in nodule ”.Results: The onset time of CE was 3 seconds and mean peak CE time was 18.8 seconds. A plateau was noted in all groups (mean duration, 6.8 seconds). Mean peak CE time and density were 16.5 seconds and 294.1 HU in group I, 18.5 seconds and 324.1 HU in group II, and 20.1 seconds and 114.0 HU in group III. The most fre-quent pattern of CE (83%) was homogeneous, and this was found in group I. The small HCC group (group I) showed a faster mean peak CE time than the large group (group III) (p