The experiment was carried out on 24 turkeys fed for 16 weeks with standard feed diets supplemented with oxidised fat with peroxide values below 5, 50, 100 and 150 meq O₂/kg of fat in groups I, II, III and IV, respectively. The fat (rapeseed oil and poultry fat in 2:1 ratio) was oxidised in controlled conditions and supplemented to feed diets in amounts from 2 to 5% in the subsequent, 4-week, turkey fattening periods. Each group was then divided into two subgroups. One of them was fed with a mix supplemented with antioxidant Hadox dry preparation (0.125 g/kg of fat) containing butylhydroxyanisole and ethoxyquine. Bird slaughter analysis was completed and breast muscles were sampled for meat quality analysis. In the breast muscles the following parameters were determined: pH value, basic chemical composition, the concentration of malondialdehyde (MDA) and in the muscle fat the fatty acid composition was analysed. The muscles underwent sensory evaluation with the use of the flavour profile method immediately after treatment in convection and steam furnace. The application of oxidised fat in the turkey feed mixture significantly decreased the bird body weight without degrading the carcass quality (except the increase in the amount of paraintestinal fat). The presence of the oxidised fat in the feed had an insignificant effect on the concentration of the unsaturated fatty acids in the breast muscle fat, however, it resulted in the increase in MDA and undesirable meat flavour profile changes. Additionally, supplementing the feed with Hadox dry antioxidant did not influence the results of turkey fattening and carcass quality, however, it decreased the concentration of MDA in the analysed muscles and reduced the intensity of the undesirable sensory properties.