BACKGROUND The end-systolic wall stress (ESS)-heart rate-corrected velocity of circumferential fiber shortening (VCFc) relationship provides a load-independent assessment of systolic function. Previously published indices may not be appropriate for studies where ethnicity may introduce bias. OBJECTIVE We sought to investigate potential differences in the ESS-VCFc relationship between the African American (AA) and Caucasian population. METHODS In all, 50 AAs and 72 Caucasians, age 3 months to 17 years, were studied. Arterial pulse tracing, phonocardiogram, electrocardiogram, and M-mode of the left ventricle were recorded. Left ventricular dimensions, functional indices, ESS, and ESS-VCFc relationships were compared between groups. RESULTS AAs had decreased indexed left ventricular end-systolic dimensions and increased septal and posterior wall thickness. AAs had increased percent fractional shortening, VCFc, and decreased ESS. Meridional ESS-VCFc relationships for the groups were similar. CONCLUSIONS Young AAs have slightly thicker ventricles with increased VCFc, lower systolic volumes, and diminished ESS compared with control subjects. Despite differences, the meridional ESS-VCFc relationships were similar and correlated closely to previously reported normal indices.