Hyaline membrane disease is attributed to a temporary lack of pulmonary surfactant. Its diagnosis, relatively easy, is based on clinical signs (respiratory distress with a 3-4 days cycle in a premature infant) and on radiological signs (reduced chest expansion, diffusion microgranulations, air-filled bronchi). In patients with few symptoms or when the disease is associated with infection or aspiration, the diagnosis is facilitated by biochemical methods, notably measurement of the lecithin/sphyngomyelin ratio and phosphatidylglycerol assay. The principal therapeutic prospects are based on the development of exogenous surfactant supply. This is either natural surfactants extracted from animal lungs or human amniotic fluid, or synthetic surfactants of varied composition. The first results of clinical trials are in favour of natural surfactants, but many technical, pharmacological and clinical problems will have to be solved before these products can be used on a wide scale.