Abstract: Objective : To study the effective diagnosis and treatment of primary malignant germcell tumors of the mediastinum and the role of operation. Methods : The clinical data of 26 patientswith primary malignant germ cell tumors of the mediastinum were retrospectively analyzed. Results : Ofthe 22 patients with surgical treatment, 11 accepted radical tumor resection, 10 partial tumor resectionand one only exploration. The operative morbidity and mortality rate was 18.2% and 9.1% respectively.12 patients accepted cisplatin-based chemotherapy regimens and 4 received radiotherapy after opera-tion. The pathologic diagnoses of 22 patients with surgical treatment were nonseminomatous malignantgerm cell tumor 12 cases, seminoma 5 cases and immature teratoma 5 cases. Three patients with imma-ture teratomas and one with embryonal carcinoma diagnosed by mediastinal scopic biopsy, lymph nodsbiopsy or transthoracic needle biopsy accepted radiotherapy or chemotherapy combined with radiother-apy. Of the 26 patients, only 2 survived longer than 5 years after operation. 17 patients were died of tu-mor relapse and distant metastases except 2 dead of operative complications. Conclusion : The treat-ment of primary malignant mediastinal germ cell tumors should emphasize combined therapy withchemotherapy as the main treatment. Surgical resection is only an adjuvant therapy for the appropriatephase of it. The opportunity of operation should depend on the patient's situation.