The shortage of cadaveric human organs for transplantation may, be alleviat
ed by the use of xenografts as a therapeutic option for end-stage organ fai
lure. Successful attempts have been made to prevent rejection of xenograft
tissues in humans. The potential spread of animal-derived pathogens to the
xenograft recipient is a complication of xenotransplantation, which must be
addressed. This can be complicated further by, the presence of new pathoge
ns, new clinical syndromes, and altered behaviour of these organisms in the
immunocompromised recipient. There is concern over the possible activation
of latent viruses, including retroviruses, from xenograft tissues. This pa
per discusses the possible dangers of transmission of animal viruses to hum
ans via xenotransplantation. (C) 2000 Elsevier Science B.V. All rights rese
rved.