Objective To observe the relationship between the detectable rate of Acetylcholine re-ceptor and presynaptic membrane antibodies in serum from Myasthenia Gravis(MG)patients with Osser-man clincal typing and concomitant thymoma and efficacy of adreno - corticosteroid therapty. MethodsAntibodies to AchR and Presynaptic membrance protein was detected by ELISA from patient with MG.Results The detectable rate from MG patients in clinical typing Osserman I and from patients not con-comitant thymoma were lower than others. Adreno - corticosteroid treat MG had good effect. ConclusionThe results indicate that detection AchR and Psm antibodies in serum was accessory diagnosetic method.