Described for the first time in 1848 by Bochdalek, congenital diaphragmatic hernia is still a hot topic. How can it be that a simple defect of the diaphragm still has a mortality rate reaching 50% in 1997, and this despite continuous progress in neonatal intensive care? If some problems remain unsolved, experimental studies over the past 30 years have raised some questions concerning the pathogenesis, and have shed some light into the pathophysiology of congenital diaphragmatic hernia. This article reviews the recent knowledge about the aetiology, pathogenesis and pathophysiology of this complex malformation.