Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that together with their tissue inhibitors (TIMPs) are important modulators of normal lung development and harmful mediators of lung damage. Several studies support the role for an imbalance of MMPs and TIMPs homeostasis in the pathogenesis of paediatric lung failure. It was verified that MMP-9 and MMP-9/TIMP-1 ratio increases in the broncho-alveolar lavage of patients with bronchopulmonary dyspasia (BPD). Maternal administration of vitamin A, once the period of retinoid-induced teratogenesis is over, results in an enhancement of lung foetal organogenesis, an increase in the lung's elastic fibres, and an increase in VEGF pulmonary and plasma levels.