Multiple mechanisms can explain a tachycardia associated or not with a heart disease. It is important to establish its origin, particularly if advanced heart disease is present, for the treatment. Complete electrophysiological study remains an important means of diagnosis. We report the case of a 39-year old man, who had a dilated cardiomyopathy since the age of 25 years and who complained of tachycardia. These symptoms were shown to be related to atrioventricular nodal re-entrant tachycardia at electrophysiological study and a specific treatment was indicated.