Objectives: We performed this study to evaluate the benefit of thymectomy in children with myasthenia gravis (MG). Methods: Over a period of 15 years from 1986 to 2001, we collected data on 30 children with MG and retrospectively reviewed the outcome of maximal thymectomy. Results: There were 23 females and seven males with a mean age of 13.2 years (range 4–16). The mean duration of the disease was 19.3 months (range 2–144). According to Osserman classification, there were 14 children in class II; 12 in class III; and four children in class IV. One child in class IV required postoperative ventilation and one was re-explored to drain a pericardial effusion secondary to central line leak. We found ectopic thymic tissue in 10 cases (33.3%). During a mean follow-up period of 53.5 months (range 9–180), complete remission was noted in 13 children (43.4%) and improvement in 14 (46.6%). The remaining three children (10%) did not improve following surgery. Univariate analysis (P<0.05) showed that ectopic thymic tissue is a significant prognostic factor for outcome. Conclusion: Maximal thymectomy appears to provide a high rate of remission and improvement in children with MG. However, the presence of ectopic thymic tissue has poor prognostic value.