We describe, to the best of our knowledge for the first time, the occurrence of idiopathic atrial flutter (AF) in two male children of a family. The two brothers are the third and sixth of seven children, and the only males. The parents do not suffer from any heart disease. The first sister died in Turkey at the age of twenty days. The parents do not know the cause of death. The fourth sister died at de age of five years, also in Turkey, probably because of meningitis. Electrocardiograms of the parents and the other three sisters are normal. Besides the unique familial occurrence, the AF themselves offer some unusual features. In the first patient, the AF could not be converted to sinus rhythm. In the second patient, the AF occurred paroxysmally, and in addition to the AF, the electrocardiogram tracings revealed paroxysmal atrial tachycardia.