Objective To study the clinical characteristics of myasthenia gravis(MG). Methods Retrospective study was done on 2 385 patients who were diagnosed at Tongji Hospital from 1956 to 1998. Results (1) There was little difference of morbidity of MG between the male and the female MG patients. The sex ratio was 1∶1.01 M∶F,but in the onset age group of 20~40 years old,there were more female patients than male ones,and the male ones were more common in the patients with their onset after 40 years old....