Background: Selenium is essential for the normal function of sperm cells and spermatogenesis. This element as an antioxidant cofactor reduces oxygen free radicals, and is expected to be effective for increasing fertility.

  Objective: The aim of this study was to determine the effect of selenium on motility, morphology and viability of sperm cells after freezing and thawing procedure. 

  Methods: This experimental study was performed on semen samples from 42 males with normal semen parameters referred to Shariati infertility center in Tehran during February and March 2013. Each sample was divided into four equal parts (two parts were washed and the other two parts were remained unwashed). 5 µg/l selenium was added to one of the washed and one of the unwashed sperm parts. Two other parts were remained untreated as control groups. Every four parts were freezed for two weeks, and subsequently they were thawed and motility, morphology, and viability of sperm cells were assessed. Data were analyzed by one-way ANOVA.

  Findings: After defreezing, motility, morphology, and viability of sperm cells in selenium groups were significantly different from control groups. 

  Conclusion: With regards to the results, 5 µg/l selenium can be used in infertility clinics in order to increase sperm quality after freezing and thawing procedure.