OBJECTIVE:Thymoma is a standard epithelial tumor. Though it is rare, it constitutes 50% of anterior mediastinal masses. Variety of immunological diseases may accompany thymoma; however, myasthenia gravis (MG) is the most frequently associated paraneoplastic syndrome. Most effective treatment for thymoma is complete surgical resection. In this study, impact of MG on prognosis of thymoma cases was examined.METHODS:Records of 61 patients who underwent surgery with diagnosis of thymoma between January 2003 and September 2016 were retrospectively reviewed. All cases were analyzed for data related to age, gender, complaint, localization of lesion, surgical procedure, histopathological diagnosis, stage, MG, and long-term follow-up results.RESULTS:Total of 58 cases were included in the study. Of those, 37 patients were male and 21 were female. Mean age was 48 years. While 24 cases of thymoma were accompanied by MG, 34 cases were not. Duration of follow-up ranged from 1 month to 155 months.CONCLUSION:It was found that in group with MG, 5-year survival rate was 87.5% while it was 82.4% in group without MG. Despite longer duration of survival in group of thymoma associated with MG, there was no significant statistical difference between groups (p=0.311).