Abstract: Objective:To investigate the incidence rate and correlation factors of depression in patients with myasthenia gravis(MG).Methods:Seventy-eight MG patients were assessed and graded with Hamilton Depression Rating scale,activities of daily living and self-designed register form.The correlation factors were analyzed by logistic regression.Results:The overall incidence rate was 60.3％.The minor,moderate and major incidence was 44.7％,34.0％ and 21.3％ respectively.The main manifestations of depression were anxiety/body,retardation,hopelessness and insomnia.The regression analysis showed that factors accounted for the occurrence of MG with depression were gender,score of activities of daily living and pyridostigmine bromide dose.Conclusions:The incidence of depression was high in MG patients.Depression with MG had a multifactorial etiology.