Objective: To explore the diagnosis and surgical treatment of primary mediastinal tumors and cysts(MTC) and the operative technique in preventing and dealing with the unexpected trauma during the operation. Methods: Two hundred and seventy-two operative patients with primary MTC were studied and analyzed. Results: Of the 272 patients

there were 77(28.3%) neurogenic tumors

75(27.6%) thymomas and 55(20.2%) teratodermoids respectively .The corresponding rate between preoperative X-ray examination and postoperative pathological examination was 73.9%.All the patients were operated through thoracotomy(266 cases)

cervical incision(4 cases)

cervical and sternotomy(2 cases) under general anaesthesia .The operative models included total resection

subtotal resection and exploration

etc. Four unexpected traumas to the superior vena cava happened

and 1 of them was repaired via an interal shunt inserted into the superior vena cava through the right atrial appendage of the heart

and cured by taking out the shunt after 2 weeks.There were 6 operative death cases (2.2%). Conclusion: Neurogenic tumor heads the list of the study

thymoma is the second and teratodermoid is the third.Chest X-ray examination is the common access to diagnose primary MTC. It is crucial for surgeons to ensure the security of the operation through satisfactory peroperative treatments

choosing correct incisions

preventing and curing trauma to the vital organs during operation.