The epidemiology and biologic characteristics of fetal tissue harvested from elective and spontaneous abortions are reviewed. The use of fetal bone marrow obtained from second trimester lost pregnancies is discussed. Allogeneic fetal tissue transplantation carried out in utero is reviewed. Data on intrauterine transplantation of human fetal bone marrow obtained from second trimester lost pregnancies into baboon fetuses are presented. The viability of this tissue, its clonogenic efficiency, engraftment, use in the future, and banking are discussed.