We present a retrospective study of the frequency and type of associated malformations and chromosomal anomalies in 42 consecutive cases of congenital diaphragmatic hernia (CDH) diagnosed in utero during the period from 1985 to 1999. In 26% (11/42) of the cases, associated malformations were detected. Chromosomal anomalies were present in 9.5% (4/42). In this group of 15 cases (15/42 = 36%) with associated malformations or chromosomal anomalies, all cases, except one, had prenatal sonographic evidence of additional problems. The survival rate of fetuses with CDH and associated malformations or chromosomal anomalies was poor (1/15). Therefore, the overall survival rate of in utero-diagnosed CDH was only 31% (13/42), while isolated left CDH had a survival rate of 52% (12/23). The in utero diagnosis of CDH implies a detailed echographic examination to exclude additional anomalies. The risk for a syndromal or chromosomal malformation becomes small when no additional anomalies are seen on ultrasound.