1. The aim of the experiment was to estimate the selenium requirement of growing male turkeys using the selenium concentrations in different organs and blood plasma and by fitting a continuous broken line to the activity of glutathione peroxidase in liver and plasma. 2. Newly hatched male BUT BIG 6 turkeys were fed either on the selenium deficient basal soybean-maize diets (selenium <0.010 mg/kg diet) adapted to the NRC (1994) and GfE (2004) recommendations for growing turkeys from 0 to 2 weeks (prestarter diet) and 3 to 5 weeks (starter diet) or the basal diets supplemented with 0.10, 0.15, 0.20, 0.25, 0.30, 0.35 or 0.40 mg selenium/kg diet as sodium selenate. Vitamin E was supplemented adequately in all diets. 3. After 5 weeks the weight in all groups (mean 2568 g) exceeded the expectations for the genotype investigated. Feed consumption and weight gain were however significantly reduced in the group receiving the selenium-deficient diet. 4. After 2 and 5 weeks selenium concentration and activity of glutathione peroxidase in the plasma and the organs examined were greatly influenced by selenium supplementation. 5. Under the conditions investigated, 0.30 mg Se/kg diet was necessary for fast-growing male turkeys to ensure maximum selenium accumulation in the organs examined and maximum glutathione peroxidase activity in plasma and liver.