Mediastinal germ cell tumor (MGCT) is histologically similar to, but is different from that in gonad glands. As to therapy, mature teratoma can be cured by resection alone. But cisplatin-based chemotherapy, often together with resection and radiation, has been playing a primary role in managing malignant MGCT consisting of seminoma and non-seminomatous MGCT. Consequently, comparably high cure rate in MGCT has been achieved. Treatment decisions should be based on the available evidence mainly obtained by retrospective studies because of the rarity of the entity. In this article, we reviewed the current strategy for MGCT, and described the outcome of 30 cases of malignant MGCT in our institution, in addition to presenting a case of nonseminomatous MGCT. Seventeen of 18 patients with malignant MGCT survived after surgery with cisplatin-based chemotherapy, while only 3 of 12 survived before cisplatin was introduced. In non-seminomatous MGCT, we now adopt cisplatin-based chemotherapy followed by surgery, including high-dose chemotherapy with peripheral blood stem cell transplantation to obtain the normalization of tumor markers. Additional chemotherapy is considered, if viable cells are found in resected specimen.