Objective To study the diagnosis and treatment of thymoma and to assess its prognostic factors.Methods The clinical data of 116 patients with thymoma were collected. A retrospective analysis was performed,by comparing the survival rate calculated by the Kaplan-Meier method with the rate of recurrence or metastasis.Results The standard posteroanterior and lateral chest radiographs were reliable means of detection of most thymomas. Myasthenia gravis was the most commonly paraneoplastic disease (25.0%,29/116). The extensive radical resection was beneficial for reducing the rate of recurrence of stage Ⅰ or stage Ⅱ thymomas (χ 2=4.941,P =0.0219). The survival time could be prolonged by postoperative radiotherapy and chemotherapy. There was a strong correlation between the clinical stage and the histological classification (according to MH classification),through which the invasive behavior of thymoma could be predicted (χ 2=19.76,P =0.007,RR=1.47). The 3- 5- and 10-year survival rates were 81.2%,67.9%,and 40.5%,respectively. Statistical analysis showed a significant negative correlation between the stage and the survival rate (χ 2=29.73,P =0.0000,RR=0.15). Conclusion The prognosis of thymoma depends mainly on the histological classification,clinical stage and multimodality treatment rather than on the paraneoplastic diseases. Objective To study the diagnosis and treatment of thymoma and to assess its prognostic factors. Methods The clinical data of 116 patients with thymoma were collected. A retrospective analysis was performed, by comparing the survival rate calculated by the Kaplan-Meier method with the rate of recurrence or metastasis. Results The standard posteroanterior and lateral chest radiographs were reliable means of detection of most thymomas. Myasthenia gravis was the most commonly paraneoplastic disease (25.0%, 29/116). The extensive radical resection was beneficial for reducing the rate of recurrence of stage Ⅰ or stage Ⅱ thymomas (χ 2 = 4.941, P = 0.0219). The survival time could be prolonged by postoperative radiotherapy and chemotherapy. There was a strong correlation between the clinical stage and the histological classification (according to MH classification) through which the invasive behavior of thymoma could be predicted (χ 2 = 19.76, P = 0.007, RR = 1.47). The 3- 5- and 10-year survival Statistical analysis showed a significant negative correlation between the stage and the survival rate (χ 2 = 29.73, P = 0.0000, RR = 0.15). Conclusion The prognosis of thymoma depends mainly on the histological classification, clinical stage and multimodality treatment rather than on the paraneoplastic diseases.