Background: The potential toxicity of copper oxide nanoparticles (CuO NPs), which are frequently employed in a variety of commercial and industrial uses, remains unknown. Hemin is the inducer of heme oxygenase 1, which exerts cytoprotective actions.Objectives: We aimed to assess the potential protective impact of hemin on the sperm of adult rats treated with CuO NPs. Material and methods: 50 adult rats were split into five groups: Group I: control, group II: animals received 40 𝜇mol/kg b.w./day of solvent, group III: rats received 40 𝜇mol/kg b.w./day of hemin, group IV: animals received 250 mg/kg b.w./day of CuO NPs and group V: rats received 40 𝜇mol/kg b.w./day of hemin followed by CuO NPs at a dose of 250 mg /kg b.w./day. Each rat was administered orally as a single dose day after day for 2 weeks. At the completion of the investigation, all rats were sacrificed. Serum sex hormones were quantified and testes homogenized for biochemical analysis. Sperm analysis was processed for light microscopic examination.Results: Nanocopper reduces fertility hormone levels leading to sperm toxicity. CuO NPs also significantly decreased the activities of antioxidant enzymes accompanied by significant elevation in the MDA levels in testes in contrast to the control group. Hemin treatment reduced the majority of the toxic impacts of CuO NPs via their antioxidative capacity. Conclusion: Administration of hemin ameliorated sex hormones, oxidative stress, lipid peroxidation and sperm characteristics in CuO NPs intoxicated rats.