The MGTX is a multi-center, single-blind, randomized study comparing thymectomy to no thymectomy in non-thymomatous myasthenia gravis (MG) patients receiving prednisone. This NINDS-sponsored project was initiated in September, 2005. The recruitment goal has been 200 subjects -100 to thymectomy plus prednisone and 100 to prednisone alone. This grant to extend the recruitment period for an additional two years and complete recruitment by November 2012 and follow patients for three years. The primary outcome and other outcome measures are unchanged from the original protocol. The plan is to continue recruitment and follow-up of all subjects, as randomized, with blinding being maintained until the last enrolled subject has completed all three years of the study. This plan is consistent from the original grant as approved by the study DSMB as well as the investigators, but will now have a longer follow-up for some patients (out to 6 years). The question being addressed by this study has challenged the MG community for over 50 years and this study is most likely the last time such a trial will be organized and/or completed.