The pulmonary microvascular endothelial cells (PMEC) lining the pulmonary vasculature form a semi-selective barrier which is critical for gas exchange and the regulation of fluid, macromolecules, and cells between the blood and the interstitial compartments in the lung. PMEC also produce angiotensin-converting enzyme to activate angiotensin, a peptide hormone which causes vasoconstriction and increases blood pressure. PMEC further plays an important role in modulating cellular properties of pulmonary mesenchymal cells and inflammatory events. Such functions of PMEC play an important role in acute lung injury, pulmonary hypertension, edema, embolism, and lung cancer development. Monkey Lung Microvascular Endothelial Cells provide an invaluable tool for understanding physiological and pathophysiological relevance in lung function and disease.