Rationale. Preterm infants exposed to mechanical ventilation and oxygen are at risk for bronchopulmonary dysplasia (BPD), a multifactorial chronic lung disorder characterized by arrested alveolar development. Recent studies have described disruption of microvascular development in BPD, characterized by primitive angioarchitectural patterns reminiscent of the canalicular/saccular stages of lung development. The molecular regulation of this BPD-associated dysangiogenesis remains undetermined. Objectives. Endoglin (CD105), a hypoxia-inducible transforming growth factor- (TGF-) co-receptor, has recently been implicated as an important regulator of angiogenesis in various neoplastic and non-neoplastic conditions. The aim of this study was to investigate the expression of endoglin and other angiogenesis-related factors in ventilated preterm human lungs. Methods. We have studied endoglin protein and mRNA expression in postmortem lungs of short-term and long-term ventilated preterm infants. Controls were age-matched infants who had lived for less than one hour. Main Results. Lungs of short-term ventilated preterm infants showed significant upregulation of endoglin mRNA and protein levels, immunolocalized to the microvasculature. Similar but more variable endoglin upregulation was noted in lungs of long-term ventilated infants with BPD. The mRNA levels of vascular endothelial growth factor (VEGF), angiopoietin-1, and their respective receptors were significantly lower in ventilated lungs than in age-matched non-ventilated control lungs. Conclusions. BPD is associated with a shift from traditional angiogenic growth factors (VEGF, angiopoietin-1) to alternative regulators such as endoglin, which may contribute to BPD-associated microvascular dysangiogenesis.