Because comprehensive normal data and the effect of observer variability for echocardiographic evaluation of regional left ventricular wall motion are not available in children or newborns, left ventricular wall motion was assessed by measuring regional area change. The study group comprised 55 infants and children with a normal heart: 15 neonates (greater than 1 week to less than 1 month old), 10 infants (greater than 1 month to less than 1 year old) and 30 children, 10 each in the age group greater than 1 year to less than 5 years, greater than 5 to less than or equal to 10 years and greater than 10 years. A combination of parasternal, apical and subcostal two-dimensional echocardiographic views was applied. After planimetry of an end-systolic and end-diastolic frame, the left ventricle was divided into eight equal segments and the percent area change calculated. Both a fixed reference and a floating system correcting for translation and rotation were applied. Intraobserver variability for percent area change measurements was 2.8 +/- 0.9% and 3.8 +/- 1% for observers 1 and 2, respectively. The mean interobserver difference of regional percent area change was 4.7 +/- 1.8%. Normal values for the eight anatomic segments were established in each echocardiographic imaging plane. The overall results were independent of the type of reference system utilized. The subcostal views yielded different results from their parasternal counterparts, probably because of differing imaging planes. These normal values establish a data base in the pediatric age range that can be used to detect abnormal segments in children at risk for developing regional left ventricular wall motion abnormalities.