Stage-specific embryonic antigen-4 (SSEA-4) is expressed in testicular germ-cell tumors (GCT) according to studies using thin-layer chromatography (TLC) immunostaining. To further understand the relationship between SSEA-4 and the histogenesis of testicular GCT, we examined the expression of SSEA-4 in 43 samples of testicular GCT either by immunohistochemical staining or by TLC immunostaining. Immunohistochemical staining detected SSEA-4 in spermatogonia from the non-tumor parts of the testis and in all of 8 samples of intratubular germ cell neoplasia unclassified (IGCNU). Immunohistochemical staining was SSEA-4 positive in all 9 seminomas, and in one yolk sac tumor and in 5 embryonal carcinomas among 9 non-seminomas. Immunostaining with TLC showed that SSEA-4 was retained in 15 of 16 seminomas and in 4 of 8 non-seminomas. These results demonstrate an antigenic link between spermatogonia, IGCNU, and testicular GCT. We suggest that SSEA-4 is associated with the histogenesis of testicular GCT.