BACKGROUND Glutamine (GLN) treatment prior to gut ischemia-reperfusion (I/R) reportedly preserves gut glutathione levels and gut barrier function. We hypothesized that intraluminal GLN during ischemia would also protect against gut I/R. METHODS After randomization to control and GLN groups, mice were exposed to 75 min (Exp 1) or 50 min (Exp 2 and 3) gut I/R. One mL of 2% GLN solution was injected into the duodenal lumen at the onset of ischemia in the GLN group, whereas controls were given normal saline. In experiment 1, survival was monitored for 120 h (n = 38). In experiment 2, blood, small intestine, and liver samples were collected at 4 h after reperfusion (n = 13). Expressions of CD11a and CD11b on myeloid cells were measured. Reactive oxygen intermediate production by myeloid cells was determined with or without phorbol myristate acetate stimulation. Glutathione levels in the small intestine and liver were also evaluated. In experiment 3, hemodynamic parameters were measured before and after I/R (n = 6). RESULTS In experiment 1, survival time in the GLN group was reduced compared with the control group. In experiment 2, GLN increased expression of CD11b and reactive oxygen intermediate with phorbol myristate acetate, compared with controls. There were no significant differences in gut or liver glutathione levels between the two groups. In experiment 3, the GLN group showed a transient but significant reduction in systolic blood pressure after reperfusion compared with the control group. CONCLUSIONS Intraluminal GLN during severe gut ischemia worsens outcomes, possibly by enhancing circulating myeloid cell priming and activation, and by disturbing hemodynamics, without increasing organ glutathione levels.