Abstract： Objective To observe the effects of recombinant human erythropoietin (rhEPO) on acute lung injury(ALI)/acute respiratory distress syndrome(ARDS)rats.Methods Twenty-four female SD rats were randomly divided into four groups:normal control group,ALI/ARDS group,low-dose EPO group,high-dose EPO group.ALI/ARDS animal models were built by intraperitoneal inj ection of endotoxin,and giving different doses of rhEPO to intervene.White blood cells,neutrophils,lymphocytes and total protein in bronchoalveolar lavage fluid(BALF)were measured.HE staining was used to observe the pathological changes in lung tissue.And lung wet/dry ratio was analysed.Results Compared with the normal control group,lung tissue was damaged seriously,lung wet/dry ratio increased,the numbers of white blood cells,neutrophils,lymphocytes and total protein in the BALF were increased significantly in the ALI/ARDS group (all P <0.01).Compared with the ALI/ARDS group,lung tissue damage was lighter,lung wet/dry ratio decreased,the numbers of white blood cells,neutrophils,lymphocytes and total protein in the BALF were significantly decreased in the low-dose and high-dose EPO groups (all P <0.05).And the efficacy of high-dose EPO group was better than that of low-dose EPO group. Conclusions rhEPO can obviously improve lung tissue inflammation in ALI/ARDS rats,reduce the pulmonary capillary permeability,restrain the pathogenesis of ALI/ARDS effectively.