Liver transplantation is the treatment of choice for many forms of liver disease. Unfortunately, the scarcity of cadaveric donor livers limits the availability of this technique. To improve the availability of liver transplantation, surgeons have developed the capability of removing a portion of liver from a live donor and transplanting it into a recipient. A few liver transplants using living donors have been performed worldwide. Our purpose was to analyze the ethics of liver transplants using living donors and to propose guidelines for the procedure before it was introduced in the United States. We used a process of "research ethics consultation" that involves a collaboration between clinical investigators and clinical ethicists. We concluded that it was ethically appropriate to perform liver transplantation using living donors in a small series of patients on a trial basis, and we published our ethical guidelines in a medical journal before the procedure was introduced. We recommend this prospective, public approach for the introduction of other innovative therapies in medicine and surgery.