Myasthenia Gravis is a chronic disorder of neuromuscular transmission characterized by weakness, fatigue of voluntary muscles, especially exacerbations and remissions, a rare disease in Korea. Special considerations are required in the anesthetic management of the myasthenic patients undergoing surgery under general anesthesia and in the postoperative respiratory management by anesthesi olgists. Authors report 8 cases of anesthesia, using N20-02-Enflurane without using nondepolarizing and depolarizing muscle relaxants for thymectomy, experienced during the year 1986~1990.