Objective:To study the application value of 125 I seed in portal vein tumor thrombus.Methods:From February 2008 to August 2008,we completed 8 125 I seeds implantations for the patients who were found portal vein tumor thrombus by B type supersound or CT.After the operations,we observed the changes of portal vein tumor thrombus.Results:Fouow-up period was six months,all portal vein tumor thrombus were decreased or disappeared,the clinical symptoms were relieved.All the patients had no adverse reactions.Conclusion:125I seed implantation has the positive effect on portal vein tumor thrombus and has rarely adverse reaction.It is an important treatment for the portal vein tumor thrombus.