Living donor liver transplantation (LDLT) was initially developed to provide suitable liver grafts for pediatric patients with end-stage liver disease. This innovation was remarkable for the prospective nature of its development and the public discussions that resolved the ethical dilemma of removing a portion of a liver from a healthy donor for the benefit of another person. Since its inception, this procedure has been uniformly adopted by most pediatric transplant centers, with excellent results. Unfortunately, liver grafts obtained from this procedure did not provide sufficient hepatocyte mass for use in adult recipients. An adult donor procedure was, therefore, developed to provide larger liver grafts, which were derived from the right lobe of the liver. Much of the driving force for adult-to-adult LDLT has been in countries that lack the health-care infrastructure for obtaining deceased donors or have cultural objections to deceased donor transplantation. In developed countries, the initial growth of adult-to-adult LDLT has been tempered by notable donor complications, including death, but it continues to have an important role in providing life-saving liver grafts for recipients who are unable to compete for deceased donor grafts in the current organ-allocation system.