Objective: To evaluate the detection rate of prenatal diagnosis and its impact on outcome in congenital diaphragmatic hernia(CDH). Study design: We retrospectively studied 51 cases of CDH registered in the Auvergne area from January 1992 to December 2003 (Birth Defect Registry of Auvergne,Institut Europé en des Gé nomutations). Our main outcome measurements were the detection rate of prenatal diagnosis, the incidence and types of associated anomalies and outcome (termination of pregnancy, in utero fetal demise, neonatal death, survivalat the time of registration). Results: Twenty-nine cases of isolated CDH were identified of which 13 were detected prenatally (45% ) at a mean gestational age of 26.1 weeks and 22 cases of CDH with associated anomalies with prenatal diagnosis of CDH or any associated anomaly in 16 (73% ; p = 0.03) at a mean gestational age of 23.9 weeks. In the prenatally detectedgroup (29 cases), there was 1 (3% ) in utero fetal death (IUFD),17 (59% ) terminations of pregnancy (TOP) and 11 (38% ) live births with early neonatal death in 7 (24% ) cases despite delivery in a tertiary care centre in 10/11 cases (four survivors = 14% ). Most of the undetected cases were isolated CDH (16/22 = 73% ) of which 1 (5% ) was a stillborn and 21 (95% ) live births with 17 survivors (77% ) although 15/21 (71% ) were not born at the tertiary care centre (p = 0.001). The overall survival rate was 41% with a large variability depending on associated anomalies and prenatal diagnosis (p < 0.0001) (prenatally detected cases:3/13 (23% ) isolated CDH and 1/16 (6% ) CDH with associated anomalies; undetected cases: 13/16 (81% ) isolated CDH and 4/6 (67% ) CDH with associated anomalies). Conclusion: Prenatal diagnosis of CDH leads to the delivery of affected babies in tertiary care centres but it remains a challenge in particular for isolated CDH cases and it is associated with a lower survival rate. Associated anomalies contribute to prenatal detection, are related to a higher TOP rate but do not facilitate the detection of diaphragmatic defect per se. Objective: To evaluate the detection rate of prenatal diagnosis and its impact on outcome in congenital diaphragmatic hernia (CDH). Study design: We retrospectively studied 51 cases of CDH registered in the Auvergne area from January 1992 to December 2003 (Birth Defect Registry of Auvergne , The main outcome measurements were the detection rate of prenatal diagnosis, the incidence and types of associated anomalies and outcome (termination of pregnancy, in utero fetal demise, neonatal death, survivalat the time of registration). Results: Twenty-nine cases of isolated CDH who were detected prenatally (45%) at a mean gestational age of 26.1 weeks and 22 cases of CDH with associated anomalies with prenatal diagnosis of CDH or any associated anomaly in 16 (73 %; p = 0.03) at the mean gestational age of 23.9 weeks. In the prenatally detected group (29 cases), there was 1 (3%) in utero fetal death (IUFD), 17 regnancy (TOP) and 11 (38%) live births with early neonatal death in 7 (24%) cases despite delivery in a tertiary care center in 10/11 cases (four survivors = 14%). Most of the undetected cases were isolated (15%) were stillborn and 21 (95%) live births with 17 survivors (77%) although 15/21 (71%) were not born at the tertiary care center (p = 0.001). The overall survival rate was 41% with a large variability depending on associated anomalies and prenatal diagnosis (p <0.0001) (prenatally detected cases: 3/13 (23%) isolated CDH and 1/16 ) CDH with associated anomalies; undetected cases: 13/16 (81%) isolated CDH and 4/6 (67%) CDH with associated anomalies). Conclusion: Prenatal diagnosis of CDH leads to the delivery of affected babies in tertiary care centers but it remains a challenge in particular for isolated CDH cases and it is associated with a lower survival rate. Associated anomalies contribute to prenatal detection, are related to a hi gher TOP rate but do not facilitate the detection of diaphragmatic defect per se.