In older children, one of the standards for indexing left ventricular mass (LVM) is height raised to an exponential power of 2.7. The purpose of this study was to establish a normal value for the pediatric age group and to determine how, if at all, LVM/height(2.7) varies in children.M-mode echocardiography was performed in 2,273 nonobese, healthy children (1,267 boys, 1,006 girls; age range 0-18 years). Curves were constructed for the 5th, 10th, 25th, 50th, 75th, 90th, and 95th quantiles of LVM/height(2.7).In children aged > 9 years, median LVM/height(2.7) ranged from 27 to 32 g/m(2.7) and had little variation with age. However, in those aged 9 years, quantiles of LVM/height(2.7) vary little, and values > 40 g/m(2.7) in girls and > 45 g/m(2.7) in boys can be considered abnormal (ie, > 95th percentile). However, for patients aged < 9 years, the index varies with age, and therefore, measured LVM/height(2.7) must be compared with percentile curves, which are provided. This variation in LVM/height(2.7) in younger children indicates that a better indexing method is needed for this age group. Nevertheless, these data are valuable in that they provide normal values with which patient data can be compared.