We sought to determine the sensitivity of detecting congenital heart defects with routine antenatal ultrasound including the four-chamber view in a population at low risk for cardiac anomalies. Neonatal outcome and anomaly databases were reviewed to identify cases of morphologic cardiac defects from 1988-1992. Of 176 cases identified, 62 (35%) had routine antenatal ultrasound including the four-chamber view. Thirteen of these 62 (21%) were diagnosed by ultrasound and 18 of the 116 (15%) total defects present were seen. Of these, only 16 of 25 (64%) defects reasonably expected to be seen by the four-chamber cardiac view alone were detected. The routine ultrasound four-chamber cardiac evaluation is limited and detection depends on the type of cardiac defect present.