Testicular germ cell tumors comprise of group of pluripotent tumors including seminomas and nonseminomas, arise from intratubular germ cell neoplasia and originate from the primordial germ cells/ gonocytes. Many well characterized markers of embryonic stem cells including CD9, PODXL and centromere-specific histone-H3-like protein CENPA are consistently expressed in TGCTs. In embryonic stem cells, pluripotency and self renewal capacities are provided by a network of OCT3/4, NANOG and SOX2. In testicular germ cell tumors, pluripotency genes OCT3/4 und NANOG are upregulated both, in seminomas and non-seminomas, while SOX2 is differentially upregulated in embryonal carcinomas only. Similar to embryonic stem cells, most histological elements of type II GCTs are sensitive to chemotherapy and irradiation. Furthermore, all invasive TGCTs show a consistent gain of the short arm of chromosome 12, as found in ES cells upon extensive in vitro culturing. Moreover, the genetic constitution of testicular germ cell tumors can also be linked to characteristics of embryonic stem cells, likely related to their specific inability to repair DNA damage and their high sensitivity to apoptotic cell death. In conclusion, testicular germ cell tumors represent embryonic cancers found in adults. Both the seminomas and nonseminomas have their specific population of stem cells representative of the primordial germ cells/gonocytes and for embryonic stem cells, respectively.