In order to evaluate the clinical significance of velamentous cord insertion (VCI) and the role of ultrasound in its diagnosis, all 82 cases of VCI during January 1985 to January 1989 at the Mount Sinai Medical Center were reviewed. The overall rate of VCI in our study (0.5%) was similar to that of previous reports. Pregnancy outcomes in VCI patients with 77 singleton gestations were compared with a control group of 15,865 patients. In contrast to the existing literature, multiparity and prior cesarean section deliveries were not increased in pregnancies with VCI. The VCI group had more intrapartum complications and a lower birthweight than the controls. Routine nontargeted obstetric ultrasound failed to detect any cases of VCI, including three cases of vasa previa. Since VCI was not identified prenatally and many of its sequelae are readily identifiable only during the intrapartum period, the potential for preemptive obstetric intervention appears to be limited. In addition, failure to diagnose apparent VCI during a routine ultrasound does not appear to be a departure from the standard of care.