PURPOSE: Recently islets transplantation has been become a hot issue in insulin dependant diabetes mellitus. This study is aimed to review the technical method of islet isolation, pruification, and microencapsulation in animal model and to study the actual ability of transplated islets on controlling hyperglycemia. Finally, we want to know whether hollow fiber model for immunoislation in islet transplantation is effective in diabetic nude mouse. Method: We use 5-6 weeks old Spregue-Dawley rats as donor. After midline incision, collagenase was infused to proximal common bile duct and pancreas was extracted. With HBSS treatment and discontinuous density gradient centrifugation, islets were isolated. From 500-1,000 numbers of islets were transplanted to 6 strepozotocin-induced nude mice via upper pole of spleen and serial blood glucose level of nude mice were checked from conjunctival veins. Also, we examined transplanted-islets in spleen histologically with light and electron microscopy. Finally, after impregnation of 500 to 1,000 numbers of islets to 2-4 hollow fibers(Amicon R, H1P30-43 type, M.W:30,000) for immunoisolation, we inserted hollow fiber into peritoneum of 3 streptozotocin-induced nude mice and checked blood glucose level serially. Results: 1) Isolation of islets from rats was done successfully and we could calculate the number of islets under microscopy. 2) In 3 diabetic nude mice without islet transplantation(control group), all of them revealed hyperglycemia above 200mg/dL after 5days from strptozotocin injection. After then, blood glucose level was ranged from 300 to 500mg/dL persistently and all of them were died after 120 days. 3) We could observe the transplabted-islets in spleen with microscopy. Blood glucose level began to be controlled after 5 days from transplantation in 3 diabetic nude mice and all of 6 diabetic nude mouses revealed normoglycemia after 25 days from transplantation. 4) Islets transplantation with holler fibers into peritoneum of diabetic nude mice was not satisfactory. Although no technical difficulty was occured, persistent hyperglycemia was observed and all of 3 diabetic nude mice were died. CONCLUSION: Though islet transplantation through spleen was sucessful in diabetic nude mouse, further study is needed to clear the cause of failure of hollow fiber model in islets transplantation.