BACKGROUND Islet transplantation is considered a potentially curative treatment for diabetic mellitus. The aim of this study was to assess the feasibility of islet transplant through the spleen. METHODS Both donor and recipient Wistar rats (BW150+/-20 g) were provided by the Animal Center of China Medical University, Shenyang, China. Islets were isolated and purified with the modified Minnesota program. 600-800IE graft islets were handpicked and transplanted through the spleen of diabetic recipients. Blood glucose and insulin were evaluated after operation every other day. IVGTT was performed 10 days after transplantation. RESULTS 300-400IE islet was procured from one donor rat. Secretion index (SI) of the glucose stress was 5.59+/-0.62, showing the graft functioning well. The diabetic rats restored normal blood glucose levels of 3.4-5.4 mmol/L (mean 4.8 mmol/L). Their insulin levels were as normal as 8.5-12.2 microIU/ml. The K value of IVGTT in the rats after transplantation was similar to the normal one. CONCLUSIONS The islets can be transplanted successfully through the spleen, while avoiding the complications caused by traditional transplantation through the portal vein, such as bleeding and portal vein hypertension. The graft islets loss can be reduced because of less centrifugation and mechanic pressure. In conclusion, transplantation through the spleen is a simple and feasible method.