Advances in assisted reproductive technology (ART) have created opportunities for preservation of the reproductive potential of young males with cancer. Semen cryopreservation is possible in most adolescents with cancer regardless of age or diagnosis. Awareness by physicians is even more essential when dealing with younger populations. Theoretically, testicular tissue from prepubertal boys facing gonadotoxic treatment could be banked for many years for spermatogonial stem cell transplantation. Male germline stem cells are the only cells in postnatal mammals that undergo self-renewal and transmit genes to subsequent generations, since all female germline stem cells cease their proliferation before birth. Future possible methods of restoring fertility might include the derivation of mature sperm cells from human embryonic stem cells. Embryoid bodies were shown to support maturation of the primordial germ cells into haploid male gametes, which when injected into oocytes round off the somatic diploid chromosome complement and develop into blastocysts.