Testicular tumors are the prevailing tumor in male of animals, accounting for about 90% of all tumors affecting the genitalia. Copper nanoparticles (Cu NPs) are emerging as promising agents for cancer therapy. The aim of this work was developed of tumors formed in the testis of mice, by exposure to arsenite (As³) in drinking water for about 6 months and treated by Copper nanoparticles. Twenty male albino Wister mice with average body weight 100 g were used and divided into four groups (five mice / group). Group 1 as control negative group; Gp. 2 (tumor group) injected I/V by Sodium arsenite (0.5 mg/kg) mice once/week for 20 weeks. Gp. 3 (treatment group) gave (Cu NPs.+ Chemotherapy protocol" Etopsoide, Cisplatin and Bleomycin" every 3 weeks and repeated 3 times; Gp. 4 (chemotherapy group) without Cu NPs. Tissue samples of testis were collected and fixed neutral formalin buffer for histopathology. In the testis of Gp.1 (control group) the seminiferous tubules have the active stages of spermatogenesis with intact germinal epithelium. In Group 2 (tumor Gp.) testicular tumor was formed large yellowish white mass of tumor with hemorrhagic area while in the histopathological examination, testis converted into solid sheet of undifferentiated anaplastic cells showing malignancy with focal areas of necrosis. Gp. 3 (treatment with Cu NPs. + Chemotherapy) was noticed markedly reduce histopathological changes at which the testis appeared neared to normal pattern and active spermatogenesis increased in most of seminiferous tubules as well as restoration of germinal epithelium. Also, interstitial edema was decreased with minimal injury of testicular tissue. Gp.4 chemotherapy treated group, there was no evidence of anaplastic cells; seminiferous tubules showed testicular degeneration with no active spermatogenesis, presence of spermatid giant cells and spermatid coagulum in addition to testicular edema. Finally, nanomaterial will be reduce the toxicity of chemotherapeutics and increase their effectiveness. We need further studies to establish other types of tumors in animals.