Background: The synthetic tripeptide feG is a novel pharmacological agent that decreases neutrophil recruitment, infiltration, and activation in various animal models of inflammatory disease. In human and rat cell culture models, feG requires pre-stimulation in order to decrease in vitro neutrophil chemotaxis. We aimed to investigate the effect of feG on neutrophil chemotaxis in a lipopolysaccharide-induced acute lung injury model without pre-stimulation. Methods: The efficacy of feG as both a preventative treatment, when administered before lung injury (prophylactic), or as a therapeutic treatment, administered following lung injury (therapeutic), was investigated. Results: Prophylactic or therapeutic feG administration significantly reduced leukocyte infiltration, ameliorated the severity of inflammatory damage, and restored lung function. feG was demonstrated to significantly decrease bronchoalveolar lavage cell infiltration, lung myeloperoxidase activity, lung oedema, histological tissue injury scores, and improve arterial blood oxygenation and respiratory mechanics. Conclusions: feG reduced leukocyte infiltration, ameliorated the severity of inflammatory damage, and restored lung function when administered prophylactically or therapeutically in a rodent model of lipopolysaccharide-induced acute lung injury, without the need for pre-stimulation, suggesting a direct rather than indirect mechanism of action in the lung.