The studies were carried out on 40 young boars of the synthetic line 990. On their 70 days of age, the boars were divided into two groups; the control group received 0.2 mg Se and 30 mg vitamin E while the experimental group received 0.5 mg Se + 60 mg vitamin E per 1 kg of feed mixtures. The feeding test was carried on from 70 days until 180 days of age. During the experiment the boars were subjected to live evaluations, i.e. testes volume, libido level, semen characteristics, as well as selenium concentration and glutathione peroxidase (GSH-Px) activity in blood serum and seminal plasma. The boars of the experimental group, compared with the control, showed significantly (P less than or equal to 0.05) higher sperm concentration and total sperm count, significantly lower (Pless than or equal to0.05) percentage of spermatozoa with major or minor morphological changes, elevated (Pless than or equal to0.05) percentage of spermatozoa with normal acrosome, and significantly higher (Pless than or equal to0.01) ORT values. GSH-Px activity was higher (Pless than or equal to0.05) in seminal plasma of the control group boars.