Objective Explore the value of video-assisted thoracoscopic extended thymectomy in the treatment of myasthenia gravis.Methods This is a prospective randomized control study.Fifty-four patients who were confirmed to be MG preoperatively from 2005 to 2008 were divided into VATS group(27 cases)and thoracotomy group(27cases).Thymectomy and dissection of all faity tissue anterior to pericardium were performed in both groups.Results When compared with thoacotomy group,VATS group had less blood loss,shorter postoperative hospital stay and time of postoperative chest drainge tube left.One patient was converted to open surgery because of the injury to the brachiocephalic vein.During a period of followed-up 624 months,symptom was improved in 81% of the patients in VATS group and 85% in thoractomy group(P>0.05).Conclusion Extened thymectomy with VATS is safe and feasible with the advantage of less invasion,less surgical trauma and pain,lower rate of complication and good curative effect.