Sperm freezing in liquid nitrogen (LN 2 ) is becoming more important because of new clinical requirements in assisted reproductive technologies (ARTs), It is done for men who may need a back-up sample stored and in cases where the man may be out-of-country at the time of ovum pick up. Sperm freezing is done by freezing prepared and washed sperm samples in liquid nitrogen through the process of vitrification and stored for several years. When the coupe decides to conceive, the frozen sperm is thawed and used in combination with IUI, IVF or ICSI.