To our previous report on the results of thymectomy for myasthenia gravis in 249 patients operated on between 1954 and 1981, we add a current review of 84 patients treated between 1982 and 1987. All patients underwent a median sternotomy, although this was performed after a bilateral submammary skin incision in most of the 57 female patients. There were no operative deaths, but one late death occurred at 5 months. During a mean followup of 3.6 years, 67 patients (80%) benefited from operation with remission achieved in 30 (36%) and improvement noted in 37 (44%). Acetylcholine receptor site antibody was present in 43 patients, of whom 19 (44%) achieved remission in contrast to 9 (27%) of the 33 patients without antibody. Hyperplasia of the excised thymus in 38 patients was associated with remission in 20 (53%) in contrast to remission in 7 (20%) of the 35 patients whose glands were "normal" or atrophic. The best prognosis was found in the 23 patients who had both receptor site antibody and thymic hyperplasia, as remission occurred in 15 of them (65%) in contrast to only 6 (27%) of the 22 patients who had neither factor. Remission rates (remissions per 1,000 patient-months of follow-up) for the present series (84 patients), the previous group (249 patients), and the overall group (333 patients) are 9.95, 6.13, and 6.62, respectively.