Antenatal and postnatal two-dimensional and gated pulsed Doppler echocardiography, beginning at 32 weeks' gestation, were used to evaluate the cardiovascular contribution to nonimmunologic hydrops in a gravida 1, para 0 nineteen year old woman. Antenatal two-dimensional imaging demonstrated a hypoplastic left heart variant of complete common atrioventricular (AV) canal. Antenatal gated pulsed Doppler examination of the fetal thoracoabdominal aorta revealed atypical pandiastolic retrograde flow. Postnatal noninvasive examination at 36 weeks' gestational age was unchanged from the prenatal study. Postmortem examination confirmed the noninvasive anatomic findings and revealed polysplenia. The mechanism of pandiastolic retrograde flow was attributable to "absence of the aortic valve," a previously unreported congenital cardiac anomaly, which resulted in severe antenatal and postnatal aortic regurgitation.