Some parts of South Africa have soils deficient in selenium leading to selenium deficiency in animals grazing pastures or fed forages produced from these areas. Selenium deficiency is not only associated with poor fertility but also occurrences of several ruminant diseases. This study evaluated the effect of selenium supplementation on reproductive activity of Saanen bucks. Forty Saanen kids aged ± 3 mo were allocated into 2 groups comprising of selenium supplemented and the control. The study was conducted over a period of 6 mo. The Kids were fed lucerne ad libitum and had free access to water throughout the experiment. The supplemented group received sodium selenite orally at 3-mo intervals. Body weight and testicular measurements were recorded every 2 weeks while sexual behaviors were evaluated at weekly intervals. Semen was collected bi-weekly using an electro ejaculator from 5 mo of age. The supplemented group were significantly (P < 0.01) heavier (21.09 ± 4.1 kg) than the control group (19.03 ± 1.5 kg) and also they had larger (P < 0 05) scrotum circumference (22.77 ± 3.2 cm vs 20.94 ± 3.7 cm) and testicular length (P < 0.01) (8.92 ± 1.61 cm vs 8.20 ± 1.71cm). Body weight had a positive correlation with the scrotal circumference; testicular length and width while it had a negative correlation with the expression of the mounting sexual behavior. Semen volume, mass motility and pH were not affected by selenium supplementation. However, the supplemented group had higher sperm concentration (2063.07 × 10⁶ mL⁻¹ vs 1748.91 × 106 mL⁻¹), live sperm (77.50 ± 13.0% vs 76.64 ± 10.5%) than the control group. The percentage of dead sperm (22.50 ± 13.0 vs 23.36 ± 10.5) and secondary abnormalities (8.07 ± 7.6 vs 8.48 ± 9.7) was lower in the supplemented group than the control group. The higher morphologically abnormal sperm cells observed from the supplemented group was mostly due to higher percentage of primary abnormalities, which cannot be contributed by selenium supplementation. It is therefore concluded that selenium supplementation increased body weight however heavier bucks expressed mounting behavior at later age than lighter bucks. Selenium supplementation also improves the sperm quality and viability.