Four cases of hypoplastic left ventricle and three cases of hypoplastic right ventricle detected sonographically prenatally are presented. A four-chamber view of the heart was abnormal in all seven cases. The sonographic appearance of the hypoplastic ventricle was variable, being smaller than normal in six of seven cases and not being identified at all in one case. Other ultrasound findings included an atrial septal defect (11 = 7); increased size of the contralateral ventricle (n = 6); nonvisualization or poor visualization of the outflow tract of the affected ventricle (11 -6), and intact ventricular septum (11 == S). In one of four cases of hypoplastic left ventricle the pregnancy was terminated; the other three infants died within 5 days after birth. One H eart disease is the most common severe congenital anomaly found in live births and is a major cause of death from congenital anomalies in childhood.1 It has been estimated that structural abnormalities of the heart and the great vessels are among the most common fetal malformations, occur~ ring more frequently than in 8 of 1,000 live births.' Unfortunately, a number of cardiac malformations produce serious morbidity and high mortality rates within the first month of life but may not be recognized prenatally. For example, hypoplastic left heart syn· drome usually results in death within 4 weeks after birth. Right ventricular outflow tract abnormalities, such as pulmonary atresia with an intact septum re-