Khayamabed R, et al. - The analysis of semen samples such as sperm concentration, motility, viability, morphology, and semen volume was carried out according to the World Health Organization criteria in order to incubate human processed spermatozoa with recombinant β-defensin 1 (500 ng/ml) for 1, 2 and 3 hr at 37°C under 5% CO₂ atmosphere and evaluation of sperm viability and motility in 59 semen samples. The result of the current study exhibited that compared with processed spermatozoa incubate in the absence of β-defensin in the studied time intervals, the incubation of spermatozoa with recombinant β-defensin notably sustained the percentage of sperm viability and motility. In summary, recombinant β-defensin 1 protein as an agent with antimicrobial activity could sustain sperm viability and motility in, in vitro condition.