All adult tissues, including the lung, have some capacity to self-repair or regenerate through the replication and differentiation of stem cells resident within these organs. While lung resident stem cells are an obvious candidate cell therapy for lung diseases, limitations exist regarding our knowledge of the biology of these cells. In contrast, there is considerable interest in the therapeutic potential of exogenous cells, particularly mesenchymal stem/stromal cells (MSCs), for lung diseases. Bone marrow derived-MSCs are the most studied cell therapy for these diseases. Preclinical studies demonstrate promising results using MSCs for diverse lung disorders, including emphysema, bronchopulmonary dysplasia, fibrosis, and acute respiratory distress syndrome. This mini-review will summarize ongoing clinical trials using MSCs in lung diseases, critically examine the data supporting their use for this purpose, and discuss the next steps in the translational pathway for MSC therapy of lung diseases. J. Cell. Biochem. 115: 1023–1032, 2014. © 2013 Wiley Periodicals, Inc.