Objectives: To study the effect of premature rupture of membranes and oligohydramnios before 20 weeks of gestation (PROM20) on acute respiratory morbidity and on short-term outcome in infants' with a gestational age greater than or equal to24 weeks. Study design: A historic cohort study was performed of all infants born after PROM20 with a gestational age greater than or equal to24 weeks between 1990 and 1999. Control infants were matched for year of birth, gestational age, and birth weight. Results: PROM20 infants had an increased acute respiratory morbidity (higher ventilator settings and increased incidence of hypoxemia, hypercapnia, and pulmonary hypertension) and a trend to more air leaks. Although not statistically different, PROM20 infants had more complications (neonatal survival, 68% vs 95%; severe intracranial hemorrhage, 31% vs 6%; chronic lung disease in surviving infants, 46% vs 17%). The relative risk for combined morbidity (death, intracranial hemorrhage, chronic lung disease) was increased (3.0, P = .019) when compared with matched control infants. However, 31% of the surviving PROM20 infants were discharged without apparent morbidity. Conclusions: Expectant treatment in women with PROM20 and present neonatal intensive care has improved the survival of PROM20 infants despite severe initial respiratory failure. However, chronic morbidity still occurred.