The frequency of diaphragmatic hernia (DH) varies, according to the studies, between 1/2000 and 1/7000. In the Languedoc-Roussillon (South of France), due to the presence of a Regional Foeto-Pathology Department and Medico Surgical Paediatric Department, it was possible to itemize all of the DH over a 24 month period (June 1989----May 1991). 20 children presenting DH (10 foetuses and 10 liveborns) were examined for a total population of 49.350 foetuses and liveborns (frequency of DH: 0.40/1000). 10 DH were associated with extra-pulmonary malformations (50%). 4 chromosome abnormalities were found (20%). Prenatal chromosome analysis in cases of ultrasound malformation detection has increased the number of karyotype abnormalities diagnosed.