Objective d -lactate is the enantiomer of l -lactate, which is measured routinely in clinical practice to assess cell hypoxia. d -lactate has been proposed as a specific marker of gut ischemia-reperfusion (IR), particularly during surgery for ruptured abdominal aortic aneurysms. The aim of this study was to compare the use of d -lactate measurement and colonic tonometry (taken as a reference method) for gut IR detection during elective infrarenal aortic aneurysm (IrAA) surgery. Design Prospective, monocenter, observational study. Setting Vascular surgery unit, university hospital. Participants Candidates for elective IrAA surgery. Interventions Patients without (controls) and with gut IR (defined as ΔCO2 >2.6 kPa) were compared retrospectively. Measurement and Main Results d -lactate levels were compared with colonic perfusion levels (ΔCO2 ), as assessed by colonic tonometry, at 7 time points during surgery and until 24 hours after surgery. d -lactate also was measured in mesenteric vein blood before and after gut reperfusion. Plasma TNF-α level was measured at the same time points to assess systemic inflammatory response. Eighteen patients requiring elective IrAA surgery were included. The ΔCO2 and TNF-α level varied significantly over time. There was a significant ΔCO2 peak at the end of clamping (2.6±1.8 kPa, p = 0.006) and a significant peak in TNF-α level after 1 hour of reperfusion (183±53 ng/L, p = 0.05). d -lactate levels were undetectable in systemic and mesenteric blood in all the patients throughout the study period. Gut IR patients (n = 6) experienced a longer overall duration of intraoperative hypotensive episodes and received more catecholamines than the controls (n = 12). Conclusions Compared with colonic tonometry, d -lactate was not a reliable biomarker of gut IR during elective IrAA surgery.