Purpose: Early incubation neural crest ablated (EXP) chick embryos develop persistent truncus arteriosus (PTA), and have high in ovo mortality compared to sham operated control embryos (SHAM). The purpose of this investigation was to assess hemodynamics in mid incubation embryos with PTA, using echocardiography. Methods: We evaluated echocardiographic hemodynamics in 10 to 18 day EXP (n=84)and SHAM (n=76) embryos. LV echocardiographic volume estimates were calibrated against plastic casts of the left ventricle. Results were analyzed using 2-way ANOV. Results: Intra and inter observer variability of hemodynamic variables were low, averaging 10 and 12%, respectively. In both SHAM and PTA hearts, ascending aortic (AAo) blood flow and stroke volume increased 65% from 10 to 18 days of incubation (p<0.001), with increasing body weight. Heart rate and left ventricular diastolic volume were equal in SHAM and EXP embryos. Ventricular function was impaired in PTA chick embryos. Left ventricular (LV) diastolic length and area (0.14 ± 0.08 cm2, SHAM; 0.13 ±0.06 PTA) were equal in the two groups. LV systolic length (0.34 ± 0.13 cm, SHAM; 0.42± 0.14, PTA) and area (0.05± 0.011 cm2, SHAM; 0.066±0.012, PTA) were higher in PTA embryos (p< 0.01). LV area ejection fraction (65 ±14%, SHAM; 50 ±14%, PTA, p < 0.0001) and volume ejection fraction(LVVEF) (81 ± 11%, SHAM; 64 ± 13%, PTA, p <0.0001) were both significantly decreased in PTA embryos. LVVEF was the same for SHAM and EXP embryos without PTA, showing decreased ejection fraction in PTA embryos is not an artifact of laser neural crest ablation. Estimated combined ventricular output was reduced an average of 49.8%(p<0.001) in PTA embryos. Incidence of pericardial effusion and significant tricuspid regurgitation increased from 15% at 12 days to 80% at 18 days.Conclusion: LV function is markedly depressed in neural crest ablated chick embryos, in the absence of significant left ventricular volume overload. Evidence of congestive heart failure in PTA embryos increases with advancing incubational age.