Objective To assess the long-term results and relevant influencing factors of extended thymectomy and medicine-alone treatment of non-thymomatous myasthenia gravis (MG) patients. Methods We retrospectively analyzed the clinical data of 174 patients with non-thymomatous MG diagnosed and treated in our department from December 2009 to April 2017, including 81 males and 93 females, aged 13-88 (47.1±17.8) years. According to the different treatment methods, the patients were divided into two groups: an operation group (91 patients receiving extended thymectomy) and a medicine-alone group (83 patients receiving medical therapy alone). The efficacy was evaluated according to the Myasthenia Gravis Foundation of America (MGFA). Survival curves of the patients were plotted using the Kaplan-Meier method to evaluate the remission rate and survival rate. Cox regression analysis was used to assess the influencing factors of the outcomes. Results The patients were followed up for 3 to 94 (39.1±26.9) months. As a result, 29 patients (31.9%) achieved complete remission in the surgery group and 13 patients (15.7%) were completely relieved in the medicine-alone group (P=0.014). Further analysis showed that treatment pattern (P=0.018) and MG type (P=0.021) were the main factors related to the efficacy. Conclusion For patients with non-thymomatous MG, extended thymectomy is superior to the medicine-alone in terms of complete remission rate and the postoperative immunosuppression ratio.