Objective.To investigate the difference of rejection in single versus combined pancreas and kidney transplantation in rats. Methods.Allograft models including simultaneous pancreas and kidney（SPK）transplant and pancreas or kidney transplant alone were established in SD-Wistar rats

rejections of pancreas and kidney in different models were compared morphologically and functionally. Results.Mean survival time（MST）of pancreas was significantly prolonged in SPK than in pancreas transplant alone（PTA）（115 days vs. 92 days

P<005）. Incidence of interstitial pancreatic rejection at grade Ⅱ and grade Ⅲ was much obvious in PTA than in SPK（429% vs. 125% at grade Ⅱ and 286% vs 63% at grade Ⅲ

P<005）. No significant difference was found in MST between SPK and kidney transplant alone（KTA）. Administration of cyclosporine A prolonged the MST of pancreas and kidney

without altering the tendency stated above. Conclusions.In SPK

the function of pancreas is protected by kidney hence the severity of rejection is reduced

whereas the function of kidney is not protected by pancreas. It suggests that different organs differ in immunoallergization and immunoregulation

and immune response tend to attack organs with greater immunoactivity

those organs with minor one could be protected. Cyclosporine A is effective on prolonging the MST of pancreas and kidney.