Recent advances in perinatal care have resulted in improved survival of extremely low birth weight infants (ELBWI). However, bronchopulmonary dysplasia (BPD) remains one of the major complications in ELBWI. BPD was originally described over 40 years ago; the clinical characteristics, epidemiology, and pathogenesis of BPD have changed markedly through this period. In this article, I have reviewed recent progress in research concerning the clinical presentation and characteristics, epidemiology, and pathogenesis of BPD.