Objective:To identify the clinical value of electromyography in hyperthyroidism diagnosis.Methods:Common electromyographic examination were applied in 30 cases with hyperthyroidism.Results:The abnormalities of electromyography were shown in all the patients even though their symptom and physical sign were not obvious at all. Conclusion:The finding suggests that excessive thyroxine might results in muscle damage and abnormal muscle electric activity. On the other hand, it is shown that electromyography is a sensible test in hyperthyroid muscle damage by which clinical muscle damage can be found. The recovery in electromyography can serves as an index which indicates hyperthyroidism has been treated effectively.