BACKGROUND Cardiac rhabdomyoma is the most common cardiac tumour in childhood and is often associated to tuberous sclerosis (TS). However, a neonatal cardiac failure was uncommonly reported as the first manifestation of tuberous sclerosis. OBJECTIVE We report a case of a cardiac tumour revealed by a heart failure in a newborn who developed later clinical manifestations of TS. METHODS We report a case of a seven-day-old girl, admitted for cardiac failure. Echocardiography discovered a voluminous single mass in the right ventricle that affected partially heart output consistent with rhabdomyoma. Clinical course improved with symptomatic treatment. Seven months later, she developed generalized seizures associated to depigmental macules and facial neuro-fibroms. Cerebral magnetic resonance imaging showed cerebral hamartoms. Subsequent eight years follow-up revealed a spontaneous regression of cardiac rhabdomyoma and no further cardiac manifestations in contrast to a slight debility and a partial control of epilepsy. CONCLUSIONS A cardiac rhabdomyoma discovered in neonates is a good indicator of TS suggesting careful followup and management