The paper describes the effectiveness of treatment of myasthenia with thymectomy in 136 patients operated on, observed in hospital and 107 examined by questionnaire on late results after 10 years. Exclusive of myasthenia with thymoma, cures were obtained in 26.4%, marked improvement in 19.6%, moderate improvement in 21.4%, improved motor strength in 27.1%, and deterioration was observed in 3.8%. The assessment was based mainly on the amount of cholinergic drugs taken. Early mortality rate was 2,4%, and late mortality 1,9%. Relation of postoperative complications/respiratory and crisis of both kinds to mortality and intraoperative pleural injury also surgical approach and anatomic variants of the thymus were discussed. An influence of the number of proliferating centers on prognosis in myasthenia after thymectomy was nor demonstrated. Thymectomy in a generally accepted and most effective method of treatment in myasthenia.