['to investigate the effect of intestinal manipulation on intestinal permeability and endotoxaemia during elective abdominal aortic aneurysm (AAA) surgery.', 'prospective randomised controlled study.', 'fourteen patients undergoing elective infrarenal AAA repair were randomised into either the transperitoneal (n=7) or extraperitoneal approach (n=7). Intestinal permeability was measured preoperatively (PO), and at day 1 (D1) and day 3 (D3) after surgery using the lactulose/mannitol absorption test. Portal and systemic blood samples were taken before clamping, at completion of proximal and distal anastomoses and immediately before abdominal wound closure, for endotoxin measurement using the chromogenic limulus amoebocyte lysate assay.', 'intestinal permeability was significantly increased at D1 (0.107+/-0.04 (mean+/-S.E.M.)) in the transperitoneal group compared to the PO level (0.020+/-0.004, p<0.05) and to the extraperitoneal group at D1 (0.020+/-0.004, p<0.05) which showed no change in comparison with the PO level. No correlation was seen between increased intestinal permeability and aortic clamp time, operation time, amount of blood lost or transfused. However, a significantly higher concentration of portal endotoxin was detected intraoperatively in the transperitoneal group of patients in comparison to the extraperitoneal group (p<0.05). There was a significant positive correlation between portal endotoxaemia and intestinal permeability (r(s)=0.955 p=0.001).'] Does intestinal manipulation during elective aortic aneurysm surgery lead to portal endotoxaemia and mucosal barrier dysfunction?