Alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV) is a rare, developmental lung disorder, which has been increasingly reported. This entity usually presents as neonatal persistent pulmonary hypertension that is unresponsive to treatment, and is known to be uniformly fatal. Recent discoveries in the genetic field, and intensive treatments, may change the natural course of this disease, permitting easier diagnosis and giving new hope for the dismal prognosis. The authors present two cases of siblings, with two years of difference, from different fathers - one of them was a first-degree and the other a second-degree cousin of the mother. Both patients were full-term babies born apparently without malformations and were sent to the nursery. Both siblings near 35 hours of age presented severe respiratory failure due to pulmonary hypertension. The outcome was fatal in both cases and at autopsy ACD/MPV was diagnosed. The authors call attention to this entity in the differential diagnosis of acute respiratory distress in early life.