The authors report their experience with allogeneic hematopoietic stem cell transplantation in infants at a university hospital in México. Five infants had one of each of the following diagnoses: acute lymphoblastic leukemia, osteopetrosis for which the patient underwent 2 procedures, acute disseminated multiorgan Langerhans cell histiocytosis, and two cases of hemophagocytic lymphohistiocytosis. The source of stem cells for grafting in 2 children was peripheral blood, and in 3 children was unrelated cord blood. A reduced-intensity conditioning regimen including fludarabine, cyclophosphamide, and melphalan was administrated. Three patients are disease-free transplant survivors without graft-versus-host disease after 46, 34, and 16 months.