This study performed on turkeys aged 1 to 98 days aimed to investigate whether different dietary inclusion levels (20, 10, 2 mg kg-1) of copper nanoparticles (Cu-NP) as a substitute for copper sulphate (Cu-SUL) affect redox and immunological status of turkeys’ tissues. No significant differences in the final body weights of turkeys were found across the dietary treatments. A comparison of the physiological effects of Cu-NP and Cu-SUL revealed equivocal metabolic responses including decreased superoxide dismutase (SOD) activity in the liver, increased SOD and catalase activities in breast muscles, decreased total glutathione concentrations in breast muscles, and decreased plasma IgY concentrations. An analysis of the antioxidant and immune status parameters in the blood, liver and breast meat of turkeys indicates that 10 mg/kg is the optimal inclusion level of additional Cu. Both two-fold higher and five-fold lower Cu supplementation levels have a negative influence on selected parameters of the antioxidant and immune status of birds. Lower supplementation levels of Cu-NP (2 and 10 mg/kg) exert similar physiological effects to Cu-SUL, whereas higher addition of Cu-NP (20 mg/kg) may negatively affect selected redox parameters and stimulate the synthesis of the proinflammatory cytokine IL-6. The results of the present study indicate that further research is needed to establish the actual dietary requirements for Cu in turkeys and the efficacy of nanoparticles as a new additional Cu source in turkey nutrition.