Semen cryopreservation (commonly called sperm banking) is a procedure to preserve sperm cells. Semen can be used successfully indefinitely after cryopreservation. For human sperm, the longest reported successful storage is 21 years. It can be used as a means of preserving fertility for men undergoing vasectomy or treatments that may compromise their fertility, such as chemotherapy, radiation therapy or surgery.
Semen is frozen using a newer flash-freezing process known as vitrification. Vitrification gives superior post-thaw motility and cryosurvival than slow programmable freezing.
Thawing at 40°C seems to result in optimal sperm motility.