Dacarbazine is one of the alkylating anticancer drugs being normally used for the treatment of a number of neoplasia. Besides targeting cancer cells, these anticancer drugs also interact with genetic material of normal cells and involve in secondary malignancy due to their genotoxic potential. As an alkylating agent dacarbazine can cause DNA damage by cross- linking DNAs and DNA and proteins, increase in reactive oxygen species production and transient depletion of intracellular glutathione. The mutagenic, carcinogenic and cytotoxic activity of dacarbazine, may be related to the induction in DNA of O 6 -methyl-guanine (O 6 - meG), a quantitatively minor but biologically important lesion. Erythropoietin (EPO) is an endogenous cytokine that is necessary for erythropoiesis. It has been shown to exert an important cytoprotective and anti-apoptotic effect in many tissues. Moreover, EPO exerts anti-inflammatory and anti-oxidant effects in several systems. But the long-term or frequent administration of rHu-EPO due to its short half-life and high doses associated with adverse side effects. So finding the new strategies to attenuate its side effects is very important. The aim of this study was to explore whether rHu-EPO loading chitosan-tripolyphosphate nanoparticles protects against dacarbazine-induced genotoxicity in HepG2 cells. For this purpose, cells were incubated with regular rHu-EPO and CS-TPP-EPONPs and dacarbazine in pre and co-treatment condition. Our results showed that both regular rHu-EPO(400IU) and CS-TPP-EPO NPs(100IU) reduced the effects of dacarbazine significantly by reduction of the level of DNA damage measured with the comet assay (p<0.0001). The most protective effect was observed with rHu-EPO when it was administrated 24 h before dacarbazine treatment. Besides, CS-TPP-EPO NPs were more effective than regular rHu-EPO.