PURPOSE:To determine the vascularity of moderately and poorly differentiated hepatocellular carcinoma (mHCC and pHCC, respectively) as observed on and depicted by computed tomography during hepatic angiography and to perform pathological correlation. MATERIALS AND METHODS:Eighty-seven consecutive patients with 89 hepatocellular carcinomas (61 mHCCs and 28 pHCCs) were surgically resected in our hospital. The degree of contrast enhancement on computed tomography during hepatic angiography of the tumors was classified into high attenuation (H), isoattenuation (I), and low attenuation (L). We also examined hepatocellular carcinomas measuring less than 4 cm in diameter. Pathologically, the number of unpaired arteries in the tumors was determined (x200 magnification). RESULTS:The number of mHCC and pHCC in each degree of enhancement (H/I/L) was 59:1:1 and 19:6:3, respectively. The number of mHCC and pHCC measuring less than 4 cm without portal invasion was 48 and 15, respectively; the number of these tumors in each degree of enhancement (H/I/L) was 47:1:0 and 11:3:1, respectively. The mean number of unpaired arteries was 8.9 +/- 4.4 in mHCC and 5.2 +/- 4.3 in pHCC, respectively. All results were statistically significant (P < 0.01). CONCLUSIONS:Our results indicated that the arterial blood supply of pHCC was lower than that of mHCC.