Abstract: Effect of dietary supplementation of organic or inorganic selenium on blood and semen selenium concentrations and semen quality was determined in 10 boars. During the 4 weeks of pre-experimental period, all boars were fed a basal diet containing 0.15 mg kg-1 of inorganic selenium. Thereafter, all cows were randomly allocated into 2 groups of five boars which were fed a basal diet supplemented with either 0.3 mg kg-1 of inorganic selenium or 0.3 mg kg-1 of organic selenium for 84 days. Blood samples were collected from all boars to determine selenium concentrations at the end of pre-experimental period and at days 49 and 84 after supplementation. Semen samples were collected at the end of pre-experimental period and at days 35, 49, 63 and 84 to determine selenium concentrations and semen evaluation. For both inorganic and organic selenium groups, blood selenium concentrations at days 49 and 84 were higher than the concentration at day 0 and the concentrations did not differ between the two groups at all sampling periods. Semen selenium concentrations at days 35, 49, 63 and 84 were higher than the concentration at day 0 for both inorganic and organic selenium groups and the concentrations did not differ between the 2 groups at days 35, 49, 63 and 84. Sperm motility parameters including motility (%), progressive motility (%), Average Path velocity (VAP, μm sec-1), Straight-line velocity (VSL, μm sec-1) and Curvilinear velocity (VCL, μm sec-1) did not differ between the 2 groups and among sampling periods. Results revealed that 0.3 mg kg-1 supplementation of either inorganic or organic selenium form in the basal diet containing 0.15 mg of selenium per kg could increase blood and semen selenium levels in the boars. With normally-fertile boars, both inorganic and organic form of selenium supplemented in the diet had similar effect on sperm motility characteristics in the boars.