Extended thymectomy is an effective treatment of myasthenia gravis. In recent years, technological development of endoscopy enables it by thoracoscopic method instead of trans-sternal approach. We perform thoracoscopic extended thymectomy via 4 trocars introduced in bilateral pleural cavity with sternum lifting method through a small incision on epigastric region. The most difficult parts in this procedure are the dissection of the left brachiocephalic vein, especially around the thymic veins and the resection of superior poles of thymus. The rate of perioperative complications by thoracoscopic approach shows no significant differences from the one by the trans-sternal operation. This technique is less invasive than trans-sternal extended thymectomy and it makes the hospital stay after the operation shorter. Since thoracoscopic extended thymectomy is a new technique, the follow-up period of the patients who underwent it for myasthenia gravis is not long enough to evaluate the effectiveness to myasthenia gravis. It is not yet shown whether the long-term results for myasthenia gravis by thoracoscopic extended thymectomy are equal to the ones by trans-sternal technique.