As islet transplantation increasingly enters the clinical arena, its coexistence with vascularized pancreas transplantation makes it necessary to reassess the questions of donor selection and allocation. In answering these questions, one must put in the balance the short-term morbidity of pancreas transplantation with the long-term attrition of islet grafts. The preferential allocation of pancreases from obese and older donors for islet isolation has been based on their association with worse pancreas transplant outcomes and better islet isolation results in islet yields. In this overview, we show that transplanted islet mass does not necessarily correlate with graft function and make the case that donor selection criteria for islet transplantation, and hence allocation rules, may need to be redefined.