The aim of the study was to review the authors’ experience with alveolar capillary dysplasia (ACD), a cause of persistent pulmonary hypertension of the neonate (PPHN) caused by decreased alveolar units, dilated anomalous pulmonary veins, thick-walled arterioles, and thickened interalveolar septa. Methods: The records of all neonates with ACD were reviewed from Children’s Hospital, Columbus, Ohio, and Sophia’s Children’s Hospital,Rotterdam, The Netherlands. The clinical characteristics and pathological findings are discussed. Results: Eight neonates were diagnosed with ACD from 1994 to 2002. Twenty-five percent (2/8) experienced respiratory distress immediately after birth, whereas 75% (6/8) had normal Apgar scores but deteriorated 1.5 hours to 30 days after birth. All infants required conventional ventilation initially; 50% (4/8) were placed on high-frequency oscillating ventilation and 87% (7/8) on extracorporeal membrane oxygenation. A premorbid diagnosis was established in 3 patients by open lung biopsy. The diagnosis of ACD was confirmed at autopsy in all patients. Conclusions: ACD is a fatal disease that should be suspected in all neonates with respiratory failure and PPHN who fail conventional therapy. Prompt diagnosis helps to avoid prolongation of costly treatment modalities in a uniformly fatal disease. An algorithm is proposed in which neonates with PPHN who fail treatment with extracorporeal membrane oxygenation are managed by open lung biopsy. The aim of the study was to review the authors’ experience with alveolar capillary dysplasia (ACD), a cause of persistent pulmonary hypertension of the neonate (PPHN) caused by decreased alveolar units, dilated anomalous pulmonary veins, thick-walled arterioles, and thickened Methods: The records of all neonates with ACD were reviewed from Children’s Hospital, Columbus, Ohio, and Sophia’s Children’s Hospital, Rotterdam, The Netherlands. The clinical characteristics and pathological findings were reported. Results: Eight neonates were diagnosed with ACD from 75% (6/8) had normal Apgar scores but deteriorated for 1.5 hours to 30 days after birth. All infants required conventional ventilation initially; 50 % (4/8) were placed on high-frequency oscillating ventilation and 87% (7/8) on extracorporeal membrane oxygenation. A premorbid diagnosis was established in 3 patients s by open lung biopsy. The diagnosis of ACD was confirmed at autopsy in all patients. Conclusions: ACD is a fatal disease that should be suspected in all neonates with respiratory failure and PPHN who failed conventional therapy. Prompt diagnosis helps to avoid prolongation of costly treatment modalities in a uniformly fatal disease. An algorithm is proposed in which neonates with PPHN who fail treatment with extracorporeal membrane oxygenation are managed by open lung biopsy.