Although small animal rodent studies indicate that there is a sexual dimorphism in the resistance to organ injury after trauma-hemorrhagic shock (T/HS), confirmatory studies are largely lacking in more clinically relevant large animal species. Thus, we tested the hypothesis that castration would reduce the susceptibility of adult minipigs to gut injury and abrogate the production of biologically active intestinal (mesenteric) lymph after T/HS. The hemodynamic response to T/HS was similar between castrated and noncastrated minipigs. Mesenteric lymph collected during the preshock period and in the trauma-sham shock (T/SS) animals did not have increased biological activity. However, T/HS-lymph from the noncastrated males increased the respiratory burst of normal neutrophils, increased endothelial cell monolayer permeability, and was cytotoxic for endothelial cells. Castration abrogated the T/HS-induced neutrophil-activating and endothelial-injurious activities of mesenteric lymph, and the biological activity of the T/HS-lymph from the castrated minipigs was not different from the T/SS animals. As compared with the T/SS minipigs, T/HS increased ileal mucosal injury and intestinal permeability. This increase in gut permeability after T/HS was manifest by in vivo bacterial translocation and by the increased passage of bacteria as well as permeability probes across intestinal segments when tested in the Ussing chamber system. In contrast, neither mucosal injury nor increased intestinal permeability was observed in the castrated minipigs subjected to T/HS. In summary, this large animal porcine study validates the notion that castration limits gut injury and the production of biologically active intestinal lymph after T/HS.