Abstract: Objective To explore the effect of modified electroconvulsive therapy(MECT) on thyroxine and sex-hormone of the of patients experiencing an episode of depression. Methods Fifty-seven patients meeting the criteria of ICD-10 for depression episode were enrolled into the study.The levels of serum free triiodothyronine(FT3),free thyroxine(FT4),thyroid stimulating hormone(TSH),triiodothyronine(T3),thyroxine(T4),testosterone(T),estradiol(E2) and prolactin(PRL) were tested at 30-minutes after the treatment and the end of treatment.Hamilton Depression Rating Scale(HAMD) was performed before and after the treatment to assessseverity of symptom.The correlations among thyroxine,sex-hormone and scores of HAMD were analyzed. Results Thyroxine had no significant changes,E2 was significantly decreased 30-minutes after the treatment(P<0.01),while PRL was significantly increased after that(P<0.01).T3,FT3 and E2were significantly increased at the end of the treatment(P<0.01).There was significant negative correlation between level of T3 and scores of retardation factor before and after the treatment(r=-0.480,r=-0.471,P<0.01).There was significant negative correlation between level of T and scores of retardation factor before and after the treatment(r=-0.412,r=-0.385,P<0.01) while no correlation among other thyroxine,Sex-hormone and scores of HAMD. Conclusion The clinical doctors can evaluate the efficacy and adjust treatment plan based on the levels of thyroxine and sex-hormone in depressive episodes patients receiving MECT.