The aim of the present study is to contribute to the knowledge of the natural history of cardiac rhabdomyoma in children with and without tuberous sclerosis. In a retrospective study, 33 children with cardiac rhabdomyoma were collected from three pediatric cardiology centres. In 30/33 patients tuberous sclerosis was associated. High prevalence of cardiac rhabdomyoma was found in infancy, with 21/23 detected before the age of 1 year, and 11/33 before 1 month of age. Cardiac manifestations were present in 19 patients: cardiac rhythm disturbances were detected in 13; in 6/33 a Wolff-Parkinson-White syndrome was documented, of which 4 presented paroxysmal arrhythmias. Obstructive or regurgitative phenomena were present in 5; and in 2 patients surgical removal proved necessary. With the exception of one tumoural mass in the right atrium, all 77 tumours were located somewhere in the ventricles, including at atrio-ventricular valve level. Because of spontaneous regression of most of the tumoural masses, treatment should at first be symptomatic, while surgical removal is required only in life-threatening conditions, as documented in 2 of our 33 patients.