Myasthenia gravis is believed to be an autoimmune disease involving morphologic and electrophysiologic disturbances of motor end plates brought about by circulating antibodies against acetylcholine receptors. Its treatment includes the use of steroids, anticholinesterase, immunosuppression and plasmapheresis. Plasmapheresis, in particular, is used either as a stand-alone temporary measure for its often dramatic, though short-lived, effect, or as an adjunctive treatment. Plasmapheresis is considered to be essential not only in preventing and treating myasthenic crisis but in preoperative management of myasthenia gravis, usually before thymectomy. the authors here report a case of myasthenia gravis that underwent preoperative plasmapheresis followed by the use of atracurium for muscle relaxation during anesthesia for thymectomy.