The first two cases in Mexico of patients with hematological malignancies treated with heterologous peripheral blood stem cell transplantation are presented. The stem cells were mobilized in the siblings by means of filgrastim; in one case, the graft was obtained from an identical twin and in the other from an HLA-identical sibling. In both instances the post-transplant aplasia lasted less than 15 years and the engraftment was complete. In the allogeneic transplantation, the graft versus host disease was treated with immunosuppression. The approximate cost of each of these procedures was 20000 U.S. dollars. The advantages of grafting heterologous peripheral blood stem cells instead of bone marrow cells are briefly discussed, focusing on economic aspects.