Incidence of pulmonary congenital malformations is studied among 46,966 babies born in a twelve year period, with special reference to 27 cases of pulmonary hypoplasia. 59.25% of these newborns were males and only 51.89% of them were born at term with normal weight. 74.0% of mortality took place in the first day of life. Hypoplasia was bilateral in 59.25% of cases and associated to other malformations in 96.29%.