Nanoparticles are used in a wide variety of fields due to their many advantages in different industries, but knowledge about the genotoxic potential of nanoparticles is rather limited. It is known that genetic changes such as mutation, recombination, and DNA damage that occur in organisms are related to many diseases. Therefore, it is very important to determine such effects of nanomaterials. Ascorbic acid (AA), one of the water-soluble antioxidant micronutrients, can be found in many vegetables and fruits and acts as a cancer preventive agent by protecting cells against oxidative damage. In this study, the genotoxic effects of cobalt nano particles (CoNP, 50nm) and cobalt chloride (CoCl2) and the antigenotoxic effect of AA against them were examined by means of both the Somatic Mutation and Combination Test (SMART) and the Single Cell Gel Electrophoresis Test (COMET) on Drosophila melanogaster. The SMART method is a fast, reliable, and economical in vivo test method based on the loss of heterozygosity genetic changes (point mutation, deletion, non-separation, and recombination) occurring in the wing imaginal disc cells. The alkaline COMET assay is a sensitive and fast technique for the detection of single-strand DNA breaks. In this study, both preliminary and concurrent applications were performed in the SMART method. It is seen that the damage induced by CoCl2 and CoNPs in the pretreated group is higher than in the simultaneous application. On the other hand, simultaneous applications were made in the COMET study, and it was observed that AA decreased the genotoxicity with statistical significance.