Pulmonary surfactant reduces alveolar contractile force by decreasing the surface tension of the alveolar lining layer. Deficiency or inactivation of pulmonary surfactant, therefore, causes massive atelectasis and hypoxia. In this research, pigs were killed by a blow to the head. The researchers obtained 10-14 times larger quantities of surfactant from the minced lung tissue than from the broncho-alveolar lavage fluid. Electro-microscopic examinations revealed many lamellar inclusion bodies in the type II cells but only a small quantity of surfactant- related substances on the alveolar surface. These findings suggest that approximately 90 percent or more of the surfactant is present in the cells. It is appropriate to conclude, therefore, that most of the surfactant seen on the alvelolar surface after death from hypoxia has been discharged from the type II cells. This article also discusses the physiological activity of the surfactant discharged by hypoxia or asphyxia, the structure of surfactant, and the mechanism of surfactant secretion in hypoxia and asphyxia. Appended supplementary research reports