The aim of the experiment was to determine the effect of a single subcutaneous application of Selevit inj. on the volume and density of ejaculates, sperm viability, level of oxidative stress (OS) and apoptosis in semen by using flow cytometry. Ten rams were divided into two groups. The experimental group, (EG; n=6) was injected one time subcutaneously with the Selevit inj. at a dose of 5 ml per animal (11 mg of sodium selenite). The control group, (K; n=4) was subcutaneously administered with physiological solution at a dose of 5 ml per animal. Samples of blood and semen were collected from each ram prior to application of Se and at day one, 14, 26, 38, 50, 62 after selenium injection. Results showed, Se concentration in the blood of EG was significantly higher, but short-term. Se concentration in the semen of the EG was significantly higher during the whole duration of the experiment (62 days). The level of OS was significantly reduced at day one, 14 and 60 after application of Selevit injection. The number of dead spermatozoa was significantly lower in the EG only at day 14 and 26 after Se application. There was only a slight increase in the percentage of sperm in the early phase of apoptosis in EG. There were no significant differences in ejaculate volume and sperm concentration between groups. Single subcutaneous injection of Selevit is sufficient enough to maintain a significant long-term increase of Se concentration in semen and has a positive effect on the level of OS, but there was no substantial influence on the quality of ejaculates.