Remarkable progress made in the past few years has brought pancreatic islet transplantation to the threshold of human clinical trials. Islet transplants have reversed diabetes in experimental animals and prevented or reversed early diabetic complications in the recipients. Methods have been developed that prevent rejection of islets transplanted across major histocompatibility barriers in rodents without requiring the continuous use of immunosuppressive drugs to maintain the transplants. A new method has been developed for isolating 40% of the islets from a single human pancreas. Based upon these accomplishments, the first phase of human clinical trials on islet transplantation was initiated during the past few months.