This study aimed to explore the association between genetic variants of matrix metalloproteinases (MMP-1 rs1799750, MMP-9 rs17576, and rs17577) and their tissue inhibitors (TIMP-1 rs4898, TIMP-2 rs2277698, and rs55743137) in the development of bronchopulmonary dysplasia (BPD) in infants from a Polish population. The gene discussed is MMP9; the disease is bronchopulmonary dysplasia.