Myasthenia Gravis(MG) is an autoimmune disease, charcterized by
   weakness of voluntary muscles. It is related to thymus gland  and
   thymectomy is preffered in treatment of MG. The aim of this study was to
   evaluate results of thymectomy during 4 years after operation.

          Twenty-five patients, who underwent thymectomy , followed for 4 years.
   We excluded 6 patients because they didn’t come back for evaluation.

          10 cases of the patients, were male and 9 cases  were female. Their age
   range were between 4 to 55 years and 15 cases were under 30 years old.
   Preoperative Osserman classification showed 17 cases were in stage II and 2
   cases were ocular type and were resistant to medical therapy in stage I. In
   result of thymus pathology, 13 cases was reported hyperplasia and 3 cases 
   had normal thymus, 2 cases with thymoma and one of them had lipoma in
   thymus . Two patients were involved myasthenic crisis, but in general 17
   cases of patients showed improvement.

          This study showed the high efficacy of thymectomy in treatment of MG;
   but it is essential to perform longer study in this field