Persistent truncus arteriosus is an uncommon congenital cardiac anomaly. In most patients, this condition is not diagnosed prior to birth. We report a case in which this uncommon cardiac anomaly was diagnosed prenatally using wide-band Doppler imaging. When diagnosing fetal truncus arteriosus, sonologists should carefully search for the origin of the main pulmonary artery and for its 2 branches. Our experience suggests that wide-band Doppler imaging facilitates the prenatal diagnosis of truncus arteriosus.