In this study, 10 male Shall sheep were used in two groups and bone marrow samples were collected and BM-MSCs isolated. Then experimental model of ARDS was induced by intrapulmonary injection of LPS to dose of 400 μg/kg. Twenty-four hours after LPS injection, 5×10 7 cells of BM-MSCs were autologous transferred in the group of treatment and 1ml PBS was infused in the group of control as intrapulmonary. Then, the symptoms of clinical, complete blood count, analysis of arterial blood gases and the concentrations of IL6,IL10,TNF-α,total protein, Ig M and albumin BAL were determined before and at times of 3,6,12,24,48,72, and 168 after transplantation/infusion. The results of the investigations 24 hours post-LPS injection(time 0) indicated the occurrence of acute in ammation which con rmed ARDS model. These changes included increase in RR, HR and RT, decrease in PO2 and SatO2 and increase in PCO2, WBC, neutrophils, macrophages, total protein, IL6, IL10, TNF-α, Ig M and albumin. But the stem/stromal cells transplantation reduced the severity of clinical signs induced by LPS, caused signi cant increase in PO 2 , SatO 2 and IL-10 and signi cant decrease in PCO 2 , the total protein, TNF-α, IL-6, Ig M, albumin, WBCs, neutrophils and macrophages at different times of sampling both in compared with before transplantation(time 0) and in compared with the group of control.While in the control group, in ammation continued until the end of the study. These results showed that BM-MSCs are able to reduce in ammation and have an important role in reconstruction of the damaged lung.