The wide uses of zinc oxide nanoparticles (nano-ZnO) in industrial, cosmetics, medicine, food production and electronics associate with increase in occupational and public exposure. Although, toxicity of nano-ZnO has been extensively studied on many different cell types and animal systems, there is a significant lack of toxicological data focus on nephrotoxic potential of nano-ZnO. In this study, the cyto- and genotoxic effects of nano-ZnO on rat kidney epithelial cells (NRK-52E) were investigated by using different assays. Nano-ZnO (10-50nm of sizes) were synthesized by sol-gel method. For the cytotoxic effect of nano-ZnO, mean of inhibition concentration (IC50) values in cell line was evaluated by MTT, Trypan Blue (TB) and Neutral Red Uptake (NRU) assays at 25.0-100.0 mu g/mL exposure concentrations. Nano-ZnO showed cytotoxic activity by acting on different targets in renal cells, with IC50 >= 73.05 mu g/mL. Comet assay was used to evaluate the genotoxicity of nano-ZnO (12.5-50.0 mu g/mL). Nano-ZnO caused statistically significant DNA damage. Our results highlight the important risk of cyto-and genotoxic effects of nano-ZnO over the kidney.