Immunohistochemical staining using the monoclonal antibody of proliferating cell nuclear antigen (PCNA) and argyrophilic nucleolar organizer region associated protein (AgNOR) staining were performed on 28 paraffin-embedded testicular tumors, and their correlation was assessed according to histological type, clinical staging and tumor markers. PCNA positive rates and AgNOR numbers in nuclei were 57.9%, 4.38 in seminomas, 63.4%, 5.79 in embryonal carcinomas, 37.7%, 2.63 in teratomas, 61.3%, 4.43 in yolk sac tumors, 79.5%, 7.12 in choriocarcinomas, and 20.9%, 3.03 in cells of the normal seminiferous tubule, respectively. In pure seminomas, the PCNA positive rates and AgNOR numbers of the stage II to III group (72.6%, 4.75) were higher than those of the stage I group (47.8%, 3.67), but there was no significant difference between the two groups. There was a significant correlation between PCNA positive rate and AgNOR number in all specimens (r = 0.76, p < 0.002). These findings indicate that PCNA and AgNOR are suitable indicators for proliferative activity of testicular tumors.