The transverse level of electrodes, A, C, E, I and M in Frank system vectorcardiography is important, since it affects the accuracy of the vectorcardiogram. 1. Using a Japanese male torso mode, the effects of shift in electrode position from the fifth to the fourth intercostal space level on lead vector were studied, and results were as follows. The magnitude of elad vector decreased in lead Z and increased in lead Y with moving all electrodes downward from the level of artificial dipole. 2. The transverse level of the center of heart vector was determined in healthy Japanese males in supine position using three-step technique. Following results were obtained. The level was upper than the fifth intercostal space, and in association with an increase in cardio-thoracic ratio, it shifted upward from the fifth intercostal space.