For the purpose of exploring the relationship between AgNORs and the biological behaviour of the testicular tumor, the value of enumeration and image analysis of AgNORs has been investigated in 10 normal testicular tissues and 49 cases of testicular tumors. The major findings were: AgNORs value for number, area, mean area, large partical number (LPN) and roundness in normal, benign and malignant tumors had significant difference (P < 0.01). The former four parameters turned larger when the tumor became more malignant, and they were significantly higher in the good prognosis group than in the bad one. LPN was higher in stage III than in stage I and II (P < 0.05), no difference was found between stage I and II. Other parameters had no significant difference in each stage. These results indicate that AgNORs is helpfull in differentiating the benign and malignant testicular tumors, in determining the degree of malignancy and offering an additional prognostic indicator in testicular tumors. Partical numbers, area and LPN were more helpfull. It had no important value in differenciating each stage.