Perinatal babies delivered in hospitals with gestation of 28 weeks to seven days after birth were monitored by National Birth Defects Monitoring Network from September 1986 to December 1993 to study the prevalence of congenital diaphragmatic hernia in China and the risk factors contributing to their prognosis. Results showed that 321 cases of congenital diaphragmatic hernia in 4,777,220 perinatal babies were detected with an incidence of 0.7 per ten thousand, a case-fatality ratio of 84.1 percent and, fetal death and stillbirth accounting for 28.1 percent of the total perinatal deaths. There was significant difference in birth weight between perinatal deaths and survival perinatal. And, 54.4 percent of the cases complicated with other congenital deformities and severe deformities in heart, lung and central nervous system accounted for the most proportion of them, which were the most important factors contributing to death. A case-fatality ratio of cases with single malformation was 74.7 percent and that of those with multiple malformation 92 percent, with a statistically significant difference. The cases diagnosed antenatally accounted for 11.3 percent of the total, and multiple malformation accounted for a large proportion of them. It indicated that proportion of antenatal diagnosis for congenital diaphragmatic hernia deformity was lower, and their perinatal case-fatality ratio was higher and their prognosis worse.