Twenty cases of hepatocellular carcinoma were examined by selective celiac and superior mesenteric arteriography. Obstruction of the main portal vein due to tumor thrombus was revealed in 7 cases and 3 of these cases had cavernous transformation of the portal vein (CTPV). The authors intended in this study to evaluate CTPV group and non-CTPV group clinically and radiologically. The results obtained are as follows: 1. The duration of illness was shorter in CTPV group than non- CTPV group. 2. There was no significant difference in tumor size between two groups ,and main portion of tumor was located in the right lobe in both groups. 3. Arterio portal shunt was present in 2 of 4 cases in non-CTPV group, but was no present at all in CRPV groups. 5. There wa no significant difference in blood chemistry between two groups. 6. CTPV may play an important role maintain the hepatic blood flow.