Myasthenia gravis was diagnosed in 48 patients between 1985 and 1991 in this Chinese community. Thymectomy was performed on 36 patients and the mean postoperative follow-up period was 49 months. Significant improvement was seen in 72% of the thymectomised patients, with 33% achieving complete remission. Patients with mild generalised myasthenia at presentation or those found to have thymic hyperplasia had the best prognosis. Patients with more severe symptoms or those with an underlying thymoma also responded favourably. Only patients with ocular myasthenia or those with a normal or atrophic thymus gland had no more than an even chance of gaining significant improvement. Although previous reports suggested a high prevalence of ocular myasthenia and of thymoma among Chinese myasthenic patients, the present study has found no evidence that they respond differently to thymectomy than their Western counterparts.