Objective:To evaluate the efficacy and safety of electrochemotherapy in treating venous malformations.Methods:Electrochemotherapy was applied to 665 patients with venous malformations of limbs and trunk,and 505 cases were followed up for half to 6 years.In this study,228 male and 277 female patients were involved.Diagnosis was made by clinical manifestations and magnetic resonance imaging.The platinum electrodes were inserted into tumor through a trocar with plastic insulating cannula percutaneously and connected with the electrochemical therapeutic apparatus in anodes and cathodes separately.Then electricity was given.The treating voltage is 6-12 V and volume 100-180 mA,the total electricity used is in general 80-100 coulombs per 1.0 square centimeter of tumors’ area.The treating time was usually from several dozen minutes to over 2 h depending on the size of the tumor.The severe cases which needed to be treated once again usually were operated after 6 months.Results:The primary efficacy end point was defined as an improvement of patients’ symptoms and a reduction in size of tumor 6 months after treatment.Effects were divided into 4 grades,and the efficacy rate decreased from grade 1 to grade 4.The efficacy turned out that 30.1%(152/505) of patients was classified as grade 1;46.3%(234/505) as grade 2;19.0%(96/505) as grade 3 and 4.6%(23/505) as grade 4.Conclusions:Electrochemotherapy shows special superiorities in treating venous malformations.It might bring a confirmed clinical efficacy with the advantages of less injury,quick recovery,simple operation and less complications. Objective: To evaluate the efficacy and safety of electrochemotherapy in treating venous malformations. Methods: Electrochemotherapy was applied to 665 patients with venous malformations of limbs and trunk, and 505 cases were followed up for half to 6 years. In this study, 228 male and 277 female patients were involved. Diagnostic was made by clinical manifestations and magnetic resonance imaging. The platinum electrodes were inserted into the tumor through a trocar with plastic insulating cannula percutaneously and connected with the electrochemical therapeutic device in anodes and cathodes separately. The treating voltage is 6-12 V and volume 100-180 mA, the total electricity used is in general 80-100 coulombs per 1.0 square centimeter of tumors’ area. The treating time was usually from several dozen minutes to over 2 h depending on the size of the tumor. severe cases which needed to be treated once again usually usually were operated after after 6 months. Results: The primary effic acy end point was defined as an improvement of patients’ symptoms and a reduction in size of tumor 6 months after treatment. Effects were divided into 4 grades, and the efficacy rate decreased from grade 1 to grade 4. The efficacy turned out that that 30.1% (152/505) of patients were classified as grade 1; 46.3% (234/505) as grade 2; 19.0% (96/505) as grade 3 and 4.6% (23/505) as grade 4. Conclusion: Electrochemotherapy shows special superiorities in treating venous malformations. It might bring a confirmed clinical efficacy with the advantages of less injury, quick recovery, simple operation and less complications.