The left ventricular muscle volume (LVMV) and the distance from the anterior chest wall to the middle of the left ventricle (D) were determined echocardiographically in 476 children as a part of the Shimane Heart Study. Correlation of the summed precordial voltage (SV1 + RV5) with LVMV was not good (r = 0.377 in males and -0.095 in females). The precordial voltage (SV1 + RV5), therefore, was corrected by the square of D to compensate the diminution of electrical potential by distance. Correlation between D2 (SV1 + RV5) and LVMV was good in males (r = 0.712) and relatively good in females (r = 0.469). Moreover, the values of D2 (SV1 + RV5) were different between both sexes at the age of 12--16 years. The thickness of subcutaneous fat may be one of the most important factors for these differences in D2 (SV1 + RV5) and correlation coefficient.