Successful sperm cryopreservation allows the opportunity for multiple ICSI cycles without the need for additional sperm retrieval procedures.Since ICSI enables even severely impaired sperm to effect oocyte fertilization, as long as sperm are viable, cryopreserved sperm can achieve rates of fertilization and pregnancy similar to fresh sperm. Cryopreservation also allows the potential for temporal separation of sperm retrieval procedures from assisted reproductive techniques. For obstructive azoospermia pregnancy rates for frozen and fresh epididymal sperm are virtually identical for NOA, fresh sperm is preferable. Freezing of isolated spermatozoa from testicular tissue is difficult because of the low number of spermatozoa present in testicular tissue and the limited sperm motility of testicular sperm, which makes documentation of sperm viability difficult. Nevertheless, anecdotal reports have indicated that it is possible to cryopreserve testicular biopsy tissue samples and subsequently extract spermatozoa after thawing with at least isolated pregnancies achieved.