Islet-cell transplantation has some advantages over vascularized pancreas transplantation, but data from clinical islet cells transplantation have shown that some serious problems need to be overcome. One of them is the storage of islet cells. We investigated methods of preserving islet cells using culture-preservation and cryopreservation. Cryopreservation is thought to be effective for long-term preservation of large quantities of islet cells, because they can be cryopreserved without loss of their physiologic activity using a relatively rapid cooling rate of 25°C/min. Moreover, in the allogenic transplantation models of cryopreservation of dissociated islet cells, there was a significant prolongation of survival time. These results suggest that cryopreservation of islet cells involves not only variable preservation methods but may also lead to a modification of graft immunogenicity.