Background and aims:  Myasthenia Gravis (MG) is a chronic autoimmune disorder of neuromuscular transmission resulting in muscle weakness. While MG reportedly occurs in all ethnic groups, relative differences in disease prevalence are yet to be determined. The aim of this study was evaluation  of incidance and other disorders with it in Kerman province of Iran. Methods: All patients with MG that referred to our department since 2007-to-2009 evaluated. The patients are all of MG diagnosed in Kerman province.Results:The average annual incidence in our study is 5.6/million population with male to female ratio 1/2. These rates in the cities with low mean temperature are higher than high mean temperature.  Thyroid diseases associated with MG is 9%, systemic lupus erythematous is 4.5%. The rate of abnormal thymus is 45% ( thymoma  16%, and thymus hyperplasia 29%). Conclusion: incidence  of myasthenia gravis in Kerman estimated 5-10/million population with female to male ratio 2/1. The incidence rate was higher in cities with low mean temperature.

Keywords: incidance, myasthenia gravis, thymectomy, thyroid diseases, thymoma, thymus hyperplasia, Kerman, Iran.