As prenatal ultrasonography becomes popular, the number of prenatal diagnosis of congenital surgical diseases is also increasing. To evaluate the impact of antenatal ultrasonography on outcome the mortality rate in neonatal surgical emergencies was studied. The authors retrospectively reviewed 281 patients (congenital diaphragmatic hernia: 44, tracheoesophageal fistula: 78, intestinal atresia: 98, omphalocele: 28 and gastroschisis: 33 who had been managed at Seoul National University Childrens Hospital, from January 1991 to December 2000. The patients were divided into two groups; group A (1991 to 1995; 139 patients) and group B (1996 to 2000; 142 patients). These two groups were subdivided into prenatally diagnosed subgroup and postnatally diagnosed subgroup. We analyzed the changes of prenatal diagnosis rate, total mortality rate, and mortality rate of subgroups. Prenatal diagnosis rate was increased significantly in group B (Group A: 24.5 % and Group B: 45.1 %). Total mortality rate of group A was 21.6 %, and that of group B was 10.6 %, showing a significant decrease in group B. However, in both group A and B, when compared antenatally diagnosed subgroup with postnatally diagnosed subgroup, the mortality rate was lower in postnatally diagnosed subgroups but statistically not significant. The authors conclude that although prenatal diagnosis rate has been increased, prenatal diagnosis itself has not resulted in significant improvement in outcome.