Sepsis is a severe, life-threatening condition primarily caused by the cellular response to infection. Sepsis leads to increased tissue damage and mortality in patients in the intensive care unit. L-Lysine is an essential amino acid required for protein biosynthesis and is abundant in lamb, pork, eggs, red meat, fish oil, cheese, beans, peas, and soy. Male albino rats were divided into sham, control, 10-mg/kg bwt L-lysine, and 20-mg/kg bwt L-lysine groups. At the end of treatment, we determined the levels of oxidative and inflammatory markers, myeloperoxidase (MPO) and catalase activities, total cell count, the wet/dry ratio of lung tissue, and total protein content. Furthermore, the effect of L-lysine on the cellular architecture of lung tissue was evaluated. L-Lysine significantly reduced the magnitude of lipid peroxidation; total protein content; wet/dry ratio of lung tissue; tumor necrosis factor-alpha, interleukin-8, and macrophage inhibitory factor levels; MPO activity; and total cell, neutrophil, and lymphocyte counts, and it increased the reduced glutathione levels and the glutathione peroxidase, superoxide dismutase, and catalase activities. A normal cellular architecture was noted in rats in the sham group, whereas proinflammatory changes, such as edema and neutrophilic infiltration, were detected in rats in the control group. L-lysine significantly ameliorated these proinflammatory changes. Thus, L-lysine has the potential for the treatment of sepsis-induced CLI.