The present invention provides a composition for freezing or freeze-drying spermatozoa or sperm heads thereof, wherein the composition enables the spermatozoa or sperm heads thereof to maintain chromosome integrity at a temperature of about +4.degree. C. to about -200.degree. C. Also provided is a container containing the composition. The present invention further provides a method for maintaining chromosome integrity of spermatozoa or sperm heads during freezing or freeze-drying. The present invention also provides methods for freezing or freeze-drying spermatozoa to obtain at least one spermatozoan capable of fertilizing an oocyte to produce a live offspring. Also provided are frozen or freeze-dried spermatozoa produced by these methods, and containers containing the frozen or freeze-dried spermatozoa. Finally, the present invention provides methods for producing a live mammalian offspring from an oocyte fertilized with a rehydrated freeze-dried (or thawed or freeze-thawed) spermatozoan.