This article examines the scientific, technical, and administrative barriers to splitting donor livers for use in two adults. The main scientific barrier is that cadaveric donor livers at their current level of postoperative function are not sufficiently large to support life in two adult recipients. However, glycogenation of livers from young donors may be a method to overcome this problem in the short term. The three technical obstacles to splitting the liver in the midplane are anatomic anomalies that complicate or prevent splitting, the means to detect these anomalies, and the surgical methods to accomplish the split. Anatomic anomalies affecting the biliary drainage and arterial supply of the liver are the most important limiting technical factors. Administrative accommodations in the current methods of organ allocation will be needed if split-liver transplantation in adults is to succeed. A nationwide view of organ allocation requires that the total number of lives saved by the procedure be the priority outcome nationally. If liver transplantation is viewed from this perspective, split- liver transplantation for adults would be a high priority, and incentives should be set to encourage it.