- Objective : To analyze retrospectively the effect of cryopreservation on donor’s sperm. Study design : Data were collected on 178 cryopreserved-thawed sperm specimens from 44 donors and 624 oocytes from 62 women, which underwent in vitro fertilization-embryo transfer (IVF-ET) treatments with donor’s sperm. Data on fresh sperm, 175 sperm specimens from 76 couples which underwent IVF-ET treatments, were used as a control group. Semen analysis was done by cell concentration, percent of motility, and quality of motility according to the World Health Organization (WHO) recommendation. Sperm quality parameters which had the strongest impact on fertilization capacity were determined using the statistical response surface model and conjoint analysis. Results : Passing sperm through Percoll column decreased sperm concentration, with no improvement in sperm motility but with a slight increase in quality of motility. Quality of motility of donor’s sperm had the strongest impact on fertilization capacity. Conclusion : Current freezing–thawing protocols of sperm cause a decrease in sperm parameters without affecting fertilization capacity. Furthermore, quality of motility of frozen–thawed sperm seems to be a significant measure of sperm fertilization capacity.