ObjectiveTo assess the long-term efficacy of extended thymectomy in the treatment of myasthenia gravis(MG) and the factors influencing the results. MethodsWe retrospectively analyzed the clinical data of 45 MG patients who underwent extended thymectomy in our hospital from January 2005 through December 2010. There were 11males and 34 females at age of 32.6(16-50) years. The overall effective rate was calculated. Univariate analysis was used to analyze the risk factors including sex, age, Osserman classification, and pathological type for outcomes. ResultsAll the patients were followed up for a mean of 58.3 months(ranged from 36 to 108 months). The overall effective rate was 80.0%(36/45) and rose with the extention of time. Age(P=0.019), pathological type(P=0.024) of thymus and Osserman classification(P=0.043) of MG were the main factors influencing the outcomes of the treatment except sex(P=0.666). ConclusionExtended thymectomy in the treatment of MG has better outcomes. And the overall effective rate rises with the extention of time.