Cardiac rhythm disorders called atrioventricular dissociation, especially the so-called dissociation with interference have been causing controversy among the cardiologists for a long time. The latter term implies an independent activity of the atria and ventricles, that is in no way connected with an orthograde atrioventricular block, and that develops in the presence of intermittent normal conductivity of sinus impulses. This disorder is always of a secondary nature and it may be due to the disorders in the formation of the primary rhythm, or conductivity of the impulse (passive form), or acceleration of the secondary rhythm (active form). The causes of such atrioventricular dissociation may lie in sinus bradycardia, sinoauricular or incomplete atrioventricular block, compensatory pauses after extra-systoles, atrioventricular and ventricular tachycardia (paroxysmal or nonparoxysmal) with a retrograde atrioventricular block, etc. Examples of ECG patterns illustrating most of the above mechanisms are presented. Due to the existence of several mechanisms that cause atrioventricular dissociation, and due to the fact that individual authors imply different meanings by the term "interference", it seems reasonable to abandon the term "dissociation with interference". In such case it would seem more appropriate to call the state a primary rhythm or conductivity disorder indicating an incomplete atrioventricular dissociation for a proper choice of therapy.