Objective To investigate the effect of alanyl-glutamine (Ala-Gln) on acute lung injury (ALI) in rats induced by sepsis and its mechanisms. Methods Forty healthy adult Wistar rats were randomly divided into a control group, a lipopolysaccharide (LPS)-induced shock group, an Ala-Gln treated group, and a glutamine (Gin) treated group. The control group received an intravenous infusion of 28 mL/kg lactated Ringer's solution(LR). The LPS-induced shock group received an intravenous administration of 25 mL/kg LR, and then 3 mL/kg (6 mg/kg) LPS (L-2880, Sigma, America). The AlaGin treated group received 4.5% Dipeptiven (25 mL/kg, equaling 0.75 g/kg Gin) immediately before 3 mL/kg (6 mg/kg) LPS. The Gin treated group received 3% glutamine (25 mL/kg, 0.75g/kg) immediately before 3 mL/kg (6 mg/kg) LPS. Serum (1 mL) was drawn via the femoral vein or cardiac puncture before LPS injection (T0) and 6 h after the administration of LPS (T1), respectively. All rats were killed 6 h after LPS infusion. The samples of pulmonary tissue and lung lavage fluid were collected after experiments. Tumor necrosis factor-α (TNF-α), interleukin-1β( IL-1β), and interleukin-8(IL-8) in the serum at T0 and T1 were detected by ELISA. Apoptosis in the lung epithelial cells was detected with TUNEL assays. The lung wet/dry(W/D) weight ratio and total protein in the bronchoalveolar lavage fluid (BALF) were measured. Results Six hours after the infusion of LPS (T1), the plasma concentrations of TNF-α, IL-1β, and IL-8 were much lower in the Ah-Gln treated group and the Gin treated group than those in the LPS-induced shock group (P < 0.05). Compared with the LPS-induced shock group, AlaGin and Gin significantly reduced the increase in the lung wet/dry weight ratio (P<0.05) and attenuated the morphological lung damage. Conclusion Intravenous administration of Ala-Gha can effectively protect the lung from sepsis induced injury.