Radix Bupleuri is a traditional Chinese herb frequently used in the prescriptions for the treatment of inflammatory diseases. This study was to determine whether the crude polysaccharides isolated from the roots of Bupleurum smithii var. parvifolium (BPs) had beneficial effects on a "two-hit" acute lung injury model in rats. A two-hit lung injury model characterized by hemorrhagic shock followed by reperfusion and intratracheal lipopolysaccharide (1 mg kg(-1)) administration was established in Wistar rats. Drugs and saline were administered 30 min after the start of resuscitation. The two-hit acute lung injury model was successfully established. After oral administration, all BPs groups ameliorated pathological injury with lessened complement C3c deposit in lung. BPs 10 and 20 mg kg(-1) diminished the ratio of wet-to-dry weight. In bronchoalveolar lavage (BAL) fluids, the protein concentration, the leukocytes counts, and the lung myeloperoxidase were significantly reduced. BPs also mediated the decreases in interleukin-6 and tumor necrosis factor-α in BAL fluids and in sera. Furthermore, BPs 20 mg kg(-1) decreased the total complement hemolytic activity. BPs had beneficial effects on two-hit acute lung injury. The mechanisms of BPs on inflammatory disease might relate to its inhibitory effect on increased production of proinflammatory mediators and on overactivation of complement.