With ever-increasing demand for liver replacement, supply of organs is the limiting factor and a significant number of patients die while waiting. Live donor liver transplantation has emerged as an important option for many patients, particularly small pediatric patients and those adults that are disadvantaged by the current deceased donor allocation system. Ideally there would be no need to subject perfectly healthy people in the prime of their lives to a potentially life-threatening operation to procure transplantable organs. Donor safety is imperative and cannot be compromised regardless of the implication for the intended recipient. The evolution of split liver transplantation is the basis upon which live donor transplantation has become possible. The live donor procedures are considerably more complex than whole organ decreased donor transplantation and there are unique considerations involved in the assessment of any specific recipient and donor. Donor selection and evaluation have become highly specialized. The critical issue of size matching is determined by both the actual size of the donor graft and the recipient as well as the degree of recipient portal hypertension. The outcomes after live donor liver transplantation have been at least comparable to those of deceased donor transplantation. Nevertheless, all efforts should be made to improve deceased donor donation so as to minimize the need for live donors. Transplant physicians, particularly surgeons, must take responsibility for regulating and overseeing these procedures. Liver Transpl 12:499–510, 2006. © 2006 AASLD.