Major developments have occurred in the field of hematopoietic stem cell transplantation since the first successful transplants from HLA-identical siblings in the late 60's. The formally experimental procedure has become established therapy for a number of congenital or acquired disorders of the hematopoietic system and for chemotherapy-sensitive malignancies. Reduced transplant-related mortality has led to a widening of indications. The present review summarizes current issues and future prospects in allogeneic stem cell transplantation. These issues and prospects will include; stem cell sources, alternative donors, graft-versus-host disease, indications and long-term survival following allogeneic stem cell transplantation.