Objective:To evaluate the effects of pre-freezing treatment of human semen samples with selenium on semen parameters after thawing procedure.Methods: Each sample was divided into four groups: two groups were washed and other two remained unwashed. 5 μg/mL of selenium was added to one of the washed and unwashed group.Results: The results showed that sperm motility in unwashed selenium-treated samples was higher compared to washed untreated samples (P<0.05). DNA damage percentage in unwashed treated samples compared to both untreated samples showed no difference (P>0.05) but in washed sperm samples, DNA damaged percentage decreased in treated samples compared to untreated ones (P<0.05). Moreover, the effect of selenium on morphology of washed treated sperms was higher than unwashed untreated samples after thawing procedure. Normal morphology percentage in unwashed treated samples was significantly higher than both unwashed samples after thawing (P<0.001). In the washed treated samples a higher number of sperms with normal morphology compared to washed untreated samples (P<0.001) were observed.Conclusion: Based on the results, we recommend 5 μg/mL of selenium should be used ininfertility clinics to increase sperm quality after freezing and thawing procedures.