We have presented a brief discussion of WHO International Histological Classification of Testicular Germ Cell Tumors. This classification divides the tumors into those of one histologic type and those of more than one type. Seven basic histological categories are recognized: seminoma, spermatocytic seminoma, embryonal carcinoma, yolk sac tumor, polyembryoma, choriocarcinoma and teratoma. Comparison of the WHO classification with the Pugh-Cameron classification reveals that except for seminoma and spermatocytic seminoma comparability between the 2 classifications is impossible. The relationship of various cell types to each other has been discussed. The origin of each cell type from malignant transformation of germ cell has been emphasized. The WHO classification has been demonstrated to correlate well with clinical tumor markers. The Pugh-Cameron classification can not be correlated with markers. More importantly, by specifying the individual components that are present in a tumor, the WHO classification provides exact information as to the possible structure of metastasis so that the urologist is in a much better position to properly manage the patient with a metastatic testicular tumor.