The Non-Structural protein 1 of Canine Parvovirus-2 (CPV2.NS1) plays a major role in viral cytotoxicity and pathogenicity. CPV2.NS1 has been proven to cause apoptosis in HeLa cells in vitro in our laboratory. Here we report that CPV2.NS1 has no toxic side effects on healthy cells but regresses skin tumors in Wistar rats. Histopathological examination of tumor tissue from CPV2.NS1 treated group revealed infiltration of mononuclear and polymorphonuclear cells with increased extra cellular matrix, indicating signs of regression. Tumor regression was also evidenced by significant decrease in mitotic index, AgNOR count and PCNA index, and increase in TUNEL positive apoptotic cells in CPV2.NS1 treated group. Further, CPV2.NS1 induced anti-tumor immune response through significant increase in CD8(+) and NK cell population in CPV2.NS1 treated group. These findings suggest that CPV2.NS1 can be a possible therapeutic candidate as an alternative to chemotherapy for the treatment of cancer.