Objective To develop a new method of immune isolation for transplanting pig islets to rat to observe the effects on diabetic rats.Method Diabetes of rat was induced by streptozotocin.Pancreas of pig was digested with type V collagenase.The pig islets were purified by density gradient centrifugation.Insulin stimulation index of the purified pig islets was evaluated.Liver of the 18 diabetic rats and 6 normal rats was exposed by operation.Capsule at one edge of the liver lobe was cut apart and separated from liver parenchyma on both sides of the lobe.An artificial cyst was constructed by a cellulose ester (CE) dialysis bag with a ball of hollow fibers in the bag,and each end of the bag was closed by a thread.Each end of the bag was stuffed into the subcapsule of each side of the liver lobe.The thread at each end of the bag was passed through a hole of the capsule at other edge of the lobe and linked to each other around the lobe to hold the artificial cyst on the liver parenchyma.Middle part of the cyst (with the ball of hollow fibers in) was put between the cuts of capsule and under the skin.The collagen solution (pH 7.4) with pig islets (4000 IEQ) was injected into the subcapsule artificial cyst of 12 diabetic rats as experiment group.The collagen solution without pig islets was injected into the subcapsule artificial cyst of 6 diabetic rats and 6 normal rats as diabetes control group and normal control group respectively.The cut was sutured.The collagen solution became a collagen gel in the artificial cysts.At 8th week of the initial transplantation,the solution with pig islets (2000 IEQ) was injected percutaneously again into the subcapsule artificial cyst of each rat of the experiment group.Rats of the three groups were raised as usual,and the levels of fasting blood glucose were measured regularly.Result The insulin stimulation index of the purified pig islets was 2.2 ± 0.2.At 1st to 8th week of the initial transplantation,the levels of fasting blood glucose in the experiment group at every time point were lower significantly than those in the diabetes control group (P＜0.01).At 13th week of the initial transplantation,there was no significant fibroplasia around the subcasule artificial cysts in the rats by visual observation.Conclusion CE dialysis bag in the liver capsule at 13th week did not show significant stimulation to the surrounding tissues.Pig islets isolated in the subcapsule artificial cyst of rats might live normally and perform hypoglycemic action.Pig islets could be percutaneously injected into the subcapsule artificial cyst.