AIM:To evaluate the therapeutic effects of segmental transcatheter arterial embolization for primary hepatocellular carcinoma, and to recognize the menifestation and clinical value of lipiodol overflow into portal veins surrounding the tumors.METHODS:A total of 50 cases of nonresectable primary hepatocellular carcinoma underwent segmental transcatheter arterial embolization. Two methods of superselective segmental catheterization were used, one was the method of wire-guiding, and the other the technic of co-axial infusion catheter.RESULTS:The 1-, 2-, 3- and 4-year cumulative survival rates of 50 cases with segmental transcatheter arterial embolization for primary hepatocellular carcinoma were 83.8%, 65.4%, 42.9% and 24.5% respectively. The in cidence of the lipiodol overflow into portal veins was 64%. The overflow of lipiodol intoportal veins, represented as 3-5 grade branches of portal veins visualized by lipiodol, was star-like or tree-like , and there was a relatively large vessel in the center surrounded with radicalized small branches of vessels.CONCLUSION:The lipiodol overflow into portal veins was one of the signs of complete embolization for tumors, and may play a partial role in embolizating the portal venous supply for hepatocellular carcinoma.