According to the literature, electrocardiographic signs of right ventricular hypertrophy have low sensitivity. The cause of this low sensitivity may be attributed to the original studies that were performed mostly in children with hypoplastic left ventricles or congenital heart abnormalities. In adulthood cases of normal or hypertrophic left ventricles, electrocardiographic right ventricular hypertrophy can only be detected during the late phase of ventricular depolarization. Two hundred four adult cardiac patients with complete noninvasive and invasive records were systematically studied by conventional and vectocardiographic methods. The terminal QRS (S wave) of the standard lead I has proved to be informative for detecting electrocardiographic signs in the presence of elevated right ventricular pressure. In cases of chronic right ventricular pressure overload (right ventricular hypertrophy) the terminal depolarization QRS vectors pointed posteriorly and to the right; therefore, a characteristic terminal S wave was represented in the standard lead I. If right and left ventricular hypertrophy were simultaneously present, the same resultant vectors pointed posteriorly and slightly to the left. In these cases, notching of the declining phase of the R wave was frequent, and a flatness of the terminal R wave portion was characteristic. The latter electrocardiographic sign has been called "simultaneous overloading of both ventricles" by the authors. The clinical utility of the new signs have also been proved by statistical methods.