In 1941, stimulated by the reports of Blalock, Mason Morgan and Riven1and of Campbell, Fradkin and Lipetz,2we undertook a study to appraise the value o thymectomy in the treatment of myasthenia gravis Although we discussed this work in previous publications,3we refrained from drawing conclusions as t( the value of thymectomy, believing that our cases were too few in number and that the period of observation was not of sufficient duration. At present we believe these objections no longer exist, and we wish to report our results as briefly as clarity permits. Greater detailsof this study appear in a report by Eaton, Clagett. Good and McDonald,3bbased on 32 cases of myasthenia gravis, which appeared in May 1949. Remissions in myasthenia gravis may occur with or without thymectomy. Therefore improvement that follows thymectomy is not necessarily due to removal of the thymus. Consequently the