Malignant transformation of germ cell tumors into somatic malignancy is uncommon. Its presentation differs from series to series, with 43 % of adult cases identified within the primary tumors and the remainder at the time of relapse or in the metastasis. Patients with stage I disease enjoy an excellent prognosis; whereas in metastatic sites when not completely resectable, the somatic type malignancies suffer a dismal prognosis. Radical surgery is significant for the prospects of cure and is standard chemotherapy for germ cell tumors; a transformation-oriented treatment can be effective for these patients. A deeper understanding of the biology of this phenomenon is essential for clinicians involved in such malignancies in order to permit a better control of the disease.