The authors analyse the results of the different trials of exogenous surfactants for the treatment of hyaline membrane disease. Whether artificial and used for prevention, or of human or animal origin and used for prevention or treatment, exogenous surfactants appear to improve the survival of premature infants. The improvement does not occur at the expense of increased morbidity. Indeed, there seems to be no increase in the frequency of patent ductus arteriosus, broncho-pulmonary dysplasia appears to be less frequent, and results on the effects of the frequency of intraventricular hemorrhage are contradictory. Current trials using new therapeutic schemes with multiple doses may further improve the protective effects of exogenous surfactants in premature infants.