We compared 42 myasthenia gravis (MG) patients with thymoma with 42 generalized MG patients without thymoma using a modified Osserman classification. The mean Osserman grades at diagnosis, 6 months, and 5 and 10 years post-thymectomy did not differ between groups. Our results indicate that thymoma is not a negative determinant for the long-term clinical outcome of MG.