The invention provides an article of manufacture comprising a substantially non-immunogenic xenograft for implantation into humans. The xenograft is a body part dissected from a transgenic 1,3-.alpha.-galactosyltransferase gene-deficient animal, wherein the cells of the body part are dead. The invention also provides methods for preparing a xenograft by removing a body part from a transgenic animal, which is 1,3-.alpha.-galactosyltransferase gene-deficient, to provide a xenograft; optionally washing the xenograft in saline and alcohol; subjecting the xenograft to a cellular disruption treatment; optionally treating the xenograft with crosslinking agents, and optionally treating the xenograft with a proteoglycan-depleting factor. The invention further provides a method for sterilizing xenograft material, having the steps of obtaining substantially non-immunogenic xenograft material; treating the xenograft material with at least one crosslinking agent; and subjecting the crosslinked xenograft material to a radiation treatment.