The aim of this study was to examine the effect supplementation of diet with 20 mg Cu/kg from copper sulphate (Cu-SUL) and/or copper amino acid chelate (Cu-AA) on the copper balance, bone mineralization status and growth performance of turkeys. A total of 840 one-day-old heavy Large White BIG-6 turkey males were randomly assigned to 4 groups: Cu-0, Cu-SUL, Cu-SUL/ Cu-AA and Cu-AA. The results of the present study confirm the Cu-requirements for growing/ fattening turkeys given by scientific bodies (e.g., NRC, INRA, GfE). The Cu unsupplemented basal diet contained 11.3 mg Cu/kg is enough for turkeys and further Cu-supplementations are not necessary. Further supplementations from inorganic and/or organic sources did not significantly improve turkeys performance and health. Plasma superoxide dismutase activity, physico-chemical properties of bone and the concentrations of Ca and P in the tibial bone were generally not affected by dietary treatment. Further Cu supplementation from inorganic and/or organic sources increase the Cu-excretion (from 808 to 1915-2164 mg per animal) and may cause additional environmental problems.