Objective To investigate the effects of ω-3 polyunsaturated fatty acid (ω-3 PUFA) on acute lung injury (ALI) in a rat model of traumatic shock. Methods Thirty-six maleWistar ratsaged 3 months were randomly assigned into 3 groups ( n = 12 each) control group (group C) ; traumatic shock group (group TS) and ω-3 PUFA + TS group (group to-3 PUFA) . Traumatic shock was induced by fracture of femur and hemorrhage according to the method described by Feeney in groups TS and ω-3 PUFA. In group ω-3 PUFA, ω-3 PUFA 2 ml/kg was injected via the caudal vein at 12 and 2 h before induction of traumatic shock. Arterial blood samples were taken at 120 min after traumatic shock was successfully induced for determination of serum concentrations of TNF-α, IL-1β, IL-10 and 8-iso-PGF2α by ELISA. The animals were then sacrificed and lungs were removed for-determination of W/D lung weight ratio and microscopic examination. Results Traumatic shock significantly increased serum concentrations of TNF-α, IL-1β, IL-10 and 8-iso-PGF2α, W/D ratio and pathologic scores of lungtissues in groups TS and ω-3 PUFA as compared with group C.ω-3 PUFA significantly attenuated traumatic shuck-induced increase in serum concentrations of TNF-α, IL-1β and 8-iso-PGF2α , W/D ratio and pathologic scores of lungtissues but further increased the serumIL-10 concentration in group ω-3 PUFA as compared with group TS. Conclusion ω-3 PUFA can significantly inhibit the svstemic inflammatory response and ameliorate traumatic shock-induced ALI.