Recently, corrected orthogonal lead systems that were designed by theoretical andexperimental data on the basis of the lead vector concepts which was originated by Burger in 1920 and developed by Schmitt, Frank, McFee, Helm and others are currently gaining favor with a view to be able to lead a electromotive force of the heart without distortion.But we have had an opinion that a lead system with distortion might be useful in vectorcardiographic diagnosis for abnormal findings of the heart in clinical practice. In corrected orthogonal lead system normal variation really decreases, while there is a possibility that a change becomes smaller in abnormal case.Generally speaking, electromotive force of the heart can be regarded as a single fixed dipole. However, one cannot help suspecting whether such observation can be esablished or not in the abnormal heart.From the clinical point of view, each lead system may be said to have a clinical value when one make a diagnosis more correctly, even though it produces some distortions.For example, the Kimura's system, which is being criticized owing to its intense distortions, is getting revaluation.Kimura proposed, in 1962, that “corrected orthogonal lead systems such as Takayasu's, Frank's, Schmitt's and sa on were introduced as the lead systems to be able to get the corrected reflection of heart vector. But the corrected orthogonal lead system is not always suitable to recognize the pathologic state in patient. At this stage for the clinical use of vectorcardiography, Kimura's lead system for left heart, Duchosal-Grishman's lead system for right heart and one of corrected orthogonal lead systems should be applied in routine”.From this point of view, a lead system with distortion might be more useful to diagnose myocardial infarction in which localized effect on electromotive force of the heart must be produced.The Frank's and the McFee's systems as corrected orthogonal lead system, Kimura's system as distorted lead system and modified Kimura 1, 2's systems which originated from the Kimura's system were compared and discussed.