The lead vectors determined with Frank's system and McFee-Parungao system for dogs using canine torso model were studied. The dog which was used for making a torso model has a body weight of 16.2kg. The dimensions of torso model were left to right of 14.0 cm, front to back 19.5 cm and height of 44.0 cm. The center of ventricular depolarization in the canine heart was determined by the chest X-Ray film. Its position was 0.75 cm to the left, 2.9 cm to the front from the body center in the fifth intercostal space. The artificial heart dipole was placed on the ventricular depolarization center of the torso model filled with 0.1% NaCl solution. Electrode position on the torso surface were designated by two quantities: the level (number I through X) and the angle in the transverse plane are each equal to 100. The level are separated by 3 cm. The dipole was placed at Ⅵ level. Image Surface was oval and located on left anteriorly and slightly inferiorly from the heart center. Normality and orthogonality of lead vectors were examined on the torso with Frank's system and McFee-Parungao system for dogs resulting the latter to be better than the former. The effect of electrode position of transverse level was tested. An anterioly shift of these electrods resulted in a increase in X and Z components of Lead X, whereas a posterioly shift tended to decrease this dimensions.