AIM: To evaluate the local expression of CTLA4 Ig gene in small bowels and its effect on preventing acute rejection of the small bowel allografts. METHODS: Groups of Wistar rats underwent heterotopic small bowel transplantation from SD rats. The recipients were randomly divided into experimental group (allografts were transfected with CTLA4Ig gene) and control group (non CTLA4Ig gene transfected). In the experimental group, the donor small bowels were perfused ex vivo with CTLA4Ig cDNA packaged with lipofectin vector via intra-superior mesenteric artery before transplantation, and the CTLA4Ig expression in the small bowel grafts post-transplantation was assessed by immunohistology. On d 3, 7 and 10 posttransplantation, the allografts in each group were harvested for the examination of histology and detection of apoptosis. RESULTS: Small bowel allografts treated with CTLA4Ig Cdna showed abundant CTLA4Ig expression after transplantation. Acute rejection of grade I on d 7 and grade II on d 10 after transplantation was noticed in the control allografts, and a dramatically increased number of apoptotic enterocytes in parallel to the progressive rejection could be recognized. In contrast, the allografts treated with CTLA4Ig cDNA showed nonspecific histological changes and only a few apoptotic enterocytes were found after transplantation. CONCLUSION: Local CTLA4Ig gene transfection of small bowel allograft is feasible, and the local CTLA4Ig expression in the allograft can prevent acute rejection after transplantation.