Objective: To determine bilateral effects of unilateral iatrogenic vas deferens trauma (UIT) on epididymal sperm characteristics and in vitro fertilizing capacity in an experimental mouse model.Methods: Experiments were performed on three equal groups each comprising six adult male mice. Following anaesthesia, UIT was induced by clamping left vas deferens with a mosquito clamp in fully locked fashion for 2 minutes in UIT group. Control-sham mice only had exposure of the left vas deferens through a groin incision. Control animals only received ceftriaxone (100 mg/kg) intraperitoneally at the day of experimental UIT induction. Ipsilateral and contralateral epididymal sperm characteristics and in vitro fertilizing capacity were evaluated after 35 days.Results: UIT significantly decreased sperm concentration, motility and viability as well as fertilization, two-cell embryos, blastocysts and hatched blastocysts rates. Moreover, incidence of DNA damage and abnormality in spermatozoa was significantly higher in UIT group.Conclusion: The findings suggest that a non-recognized iatrogenic vas deferens trauma may have detrimental effects on spermatozoa leading to infertility.