Thymectomy is an accepted therapeutic modality for patients with myasthenia gravis. The selection of patients for operation, the timing of operation and the surgical approach are still controversial. We reviewed 82 patientsraged 13 to 66 years; mean age, 37.7 years treated with transsternal thymectomy between January 1983 and December 1994. Patients were symptomatically staged according to the modified Osserman's classification. There was one hospital death and postoperative follow-up was obtained on 75 patients. During a mean follow up of 56.9 months, 64 patients (85.3%) benefited from the operation with complete remis ion achieved in 28(37.3%). The thyroid disease was present in 8 patients, of whom 7(87. 5%) achieved complete remission in contrast to 21 (31.3%) of the 67 patients without thyroid disease. The disease duration less than 2 years in 32 patients was associated with complete remission in 16 (50%) in contrast to remission in 12(27.4%) of the 43 patients whose disease duration was more than 2 years. In conclusion, the complete remission rate after transsternal thymectomy was affected by the presence of thyroid disease and disease duration. Myasthenia gravis with late onset(>40 years), thymoma pathology, old age and male gender appear to decrease the complete remission rate after transsternal thymectomy, although it was not statistically significant. There was no difference of complete'remission rate between normal and hyperplasia of thymus. Transsternal thymectomy was found to be beneficial in most patients with myasthenia gravis, but the majority of patients with ocular disease did not b nefit from the operation.