Effective clinical trials of pancreatic islet transplantation may now be a realistic goal, especically if ways are found to store. Islets and prevent rejection. One approach would be to establish a tissue bank containing islets with a wide variety of HLA phenotypes, thus providing sufficient tissue to treat individual patients while increasing the likelihood of matching donor and recipient for HLA. The most appropriate method for long- term storage af islets is to preserve them in a deeply frozen state. In the study presented here, it is our aim to determine the effect of cryopreservation on the recovery, merphology, function and viabihty of defined number of isolated rat islets cryopresserved by simple and inexpensive nethod. The results obtained were as follows: 1) Two hundred fiity islets from each of 6 donors underwent cryopreservation and the number of islets retrieved fell to 190+-10 corresponding to an overall recovery of 76% after thawiag. 2) The mean amounts of insulin secreted by islet before and after cryopressvation during stimulation with 200mg/dl glucose were 23.8 and 22.l pU/islet/ 90min. Respectively, There was no significant difference. 3) On phase microscopy, some islets were fragmentary after cryoprwervation, and in the electronmicroscopic studies, cell microorganells, nuclei and cytoplasmic membranes were intact but cytoplasmic vacuolations were noted after cryopresservation. 4) five streptozotocin induced diabetic rats were transplanted into portal vein with 800-1000 cryopreserved islets. Transplanted diabetic rats were returned to normal blood sugar a few days later. Islet cells were observed in potal venuleof transplanted diabetic liver. In conclusion, this technique for cryopreservation which is very Simple and inexpensive is very appropriate method far long-term storage off islet without altering function and survival of islet cells.