Electrocardiographic, vectorcardiographic and phonocardiographic changes were studied before and after surgical correction of isolated pulmonic stenosis. 1. Before operation, the maximal right ventricular systolic pressure were correlated well with the T wave changes, such as mean electrie T axis, direction of maximal T vector in each plane, spatial maximal QRS-T angle, ratio of spatial magnitude of T to QRS vector, and the QRS wave changes, such as height of Rv(1), sum of Rv(1) and Sv(5), direction of maximal QRS vector in frontal plane, rotation of QRS loop in horizontal plane, configuration of QRSv(1). After operation, in addition to those above, R/Sv(1), Rv(1)+Sv(5)/Sv(1)+Rv(5) and mean electric QRS axis tended to improve much more within the first one year after operation than thereafter. 2. The appearance of RBBB type were found more frequent after operation than before, and thought to be due to the decreasing right ventricular systolic overloading, or its combination with operative invasion to peripheral network of right bundle branch. 3. The more or less abnormal findings were revealed in twenty one cases, the remaining one was appreciated to be normal one hundred and twenty five months after operation.