Among 137 thymectomized patients with nonthymomatous myasthenia gravis (MG), six were reoperations. Thymectomy had initially been performed by the transcervical approach, but was ineffective. Extended thymectomy was then performed by median sternotomy. The reoperations revealed residual thymus (average weight, 19 gm) in all cases. Postoperative courses were favorable in three patients and unfavorable in three others. The latter had received high-dose steroid therapy before the second operation. We conclude that total thymectomy by the transcervical approach is almost impossible, and that reoperation may accelerate improvement in some cases.