From 1974 to December, 1992, as reported by the International Islet Transplant Registry, there have been 175 adult islet allografts worldwide. Ninety-eight of these transplants have been performed since 1989. Eleven patients with Type I diabetes mellitus who have received islet allografts since 1989 have achieved insulin-independence for variable periods of time. As of June, 1993, four patients remain insulin-independent (from > 127 to > 326 days). Insulin-independence after human islet cell transplantation is not yet a consistent achievement. Several key issues in pancreas procurement, islet cell isolation, islet preservation, islet engraftment and the prevention of islet allograft rejection still need to be addressed. The expansion of current clinical trials should be limited to patients who are taking or who require immunosuppressive drugs for other reasons (kidney or liver transplant recipient) since the risks of chronic immunosuppression probably outweight the risks from chronic diabetes, although as we are able to induce a more specific state of immunosuppression this rationale may become debatable.