The paper aimed at applying the hawthorn preparation Interactum crataegi at the dose of 0.35 ml/kg b.w./daily as an additive to drinking water for turkey hens. The study was carried out using 6-week-old turkey-hens of heavy BIG 6 type. Birds were divided into two groups: control and experimental, in which turkey hens were administered plant-origin hawthorn preparation in the amount of 0.35 ml/kg b.w./daily. For the whole experiment, birds had ad libitum standard full-dose mixtures (Provimi Polska) according to a program including 5 feeding periods. Superoxide dismutase and catalase activities, total antioxidant potential of a plasma, as well vitamin C and Fe, Zn, Cu contents were determined in turkey-hen's blood. The increase of the total antioxidant potential (FRAP) in experimental birds’ blood along with superoxide dismutase (SOD) activity were recorded at the end of the experiments. The superoxide dismutase activity increase was correlated with copper concentration increase.