The indication for thymectomy in myasthenia gravis still is controversial, and it is uncommon to find in the present days studies comparing conservative treatments, due to the widespread surgical treatment adopted in most centers. We studied 65 cases divided into three groups of patients: (1) 15 thymectomized patients and 50 with conservative treatment; (2) 15 thymectomized patients paired with 15 on conservative treatment; (3) 49 patients treated with corticosteroids against 16 without corticosteroids. These three groups where compared regarding age, age when the symptoms began, disease duration, clinical severity and functional scale, studying remission, stability or worsening of the symptoms and death rate after several years of treatment. It was found a reduction of the symptoms (p < 0.05) in the thymectomized patients of group 1; the remaining parameters of all three groups did not show any statistical significance. These results suggest that the type of treatment did not interfere with evolution of myasthenia gravis in this group of patients.