Objective To discuss the value of extra-hepatic artery embolization in the treatment of giant hepatocellular carcinoma (HCC).Methods Thirty-five patients with giant HCC were enrolled in this study.Angiography was performed on celiac artery at the 1st time of transcatheter arterial chemoembolization (TACE),and on superior mesenteric artery and diaphragmatic artery right internal thoracic artery,right intercostal artery,during the 2nd and next TACEs to explore extra-hepatic blood supply of the tumors.Results In all 35 patients,49 extra-hepatic arterial branches were found,and 46 were treated with chemoembolotherapy,3 with super selective chemotherapy.Diaphragmatic artery often served as extra-hepatic arterial blood supply,and then internal thoracic artery,intercostal artery,etc.Conclusion Super selective chemoembolization or chemothrephy of extra-hepatic blood supply arteries can improve the therapeutic effect of TACE for giant HCC.