Because of a fundamental role of the lung epithelial and endothelial cells, neutrophils, macrophages, T-lymphocytes, vascular smooth muscle cells, etc., in the pathogenesis of ALI/ARDS, inhibition of PDE3, PDE4, and PDE5 isoforms distributed in the mentioned cells by either nonselective PDE inhibitors or selective PDE3, PDE4, and PDE5 inhibitors is of a particular interest in ARDS. Here, PDE4A is linked to acute respiratory distress syndrome.